Dead Tx module troubleshooting

[mighty pecan]

Hi,
a few weeks ago I made the jump to ELRS by purchasing a Namimno flash OLED Tx. Long story short, I successfuly flashed it to the latest version and it worked great, until it didn't. I started using the BT gamepad function for my sim sessions and the last one lasted 2.5 hours, with the controller on my lap. The tx module started acting up, at first it stopped detecting the transmitter (NO HANDSET) message on the oled. After rebooting the transmitter the module got stuck on the boot screen. Now the module does not power up from usb or transmitter bay at all, no lights or display. At the time the tx power was set to 50 or 100 mw and the fan was off.

I have some questions that arise from this
1.) Is there an "easy" way to identify if the esp or RF chip got fried physically or if it's just bricked software-wise and still salvageable.
2.) Would a overheated radio chip even cause the esp and oled side to stop working?
3.) Does the main RF circuit even power on while bluetooth gamepad is active? (And if yes, that should be talked about more).

[reef void]

If it's says NO HANDSET then it's not getting a connection from the controller. This can be because the pins are not making a good connection in the JR bay.
The RF part of the circuit is disabled in Bluetooth mode.

[mighty pecan]

If RF is disabled then overheating seems somewhat unlikely. It is possible that the module moved around physically inside the bay causing loss of contact with the pins, but now the problem is that i have a bricked unresponsive module and i'm looking for ways to diagnose it.

[mighty condor]

reflash it via uart/usb

[mighty pecan]

The configurator can see a com port but can't get trough when flashing

[mighty condor]

post the !log please

[young ferry]

See the following image to save a log file from the configurator

https://cdn.discordapp.com/attachments/798006228450017290/1025339571979960340/LogSaveToFile.jpg

[mighty condor]

post screenshot of the device manager windows app, with the module plugged in into usb, expand ports device grouping

[mighty condor]

open the module and make sure the switch at the bottom left is set to the right

[mighty pecan]

it was by default I think

That's the switch between the main esp and backpack iirc

either way, just confirmed that it is to the right, on the marking that reads "32" as opposed to "85" on the left

[mighty condor]

it's as if the esp32 got desoldered from the board

[mighty pecan]

I mean i have a rework station, might just give it a shot if that's my last resort

still really weird

[mighty condor]

inspect the module. and see if there were tell-tale signs

[mighty pecan]

what's the odds that it popped from prolonged bluetooth action

It's not like there's a huge hole in one of the ICs

[mighty condor]

I can't tell if that is even possible to heat up when in ble mode

[mighty condor]

try flashing via uart again, but with pressed "boot 2" during usb plug in (manually putting the esp32 into boot mode)

[mighty pecan]

No luck with that either

same result

[mighty condor]

have you successfully flashed the module via usb before? just to rule out that the ch340 chip has flaky connection with the board

[mighty pecan]

Yes, one variable being that i flashed it using a different pc

But it was flashed to the latest version of elrs

[mighty condor]

it's being detected by this computer so I would rule that out..

[mighty pecan]

that's the thing, it's detecting the usb chip but nothing down the line

any chance the bootloader on the esp32 got messed up?

before I assume it's physically dead or else

[mighty condor]

I don't think it's that easy to "mess up"

[mighty pecan]

I tried a couple more things like flashing a 2.x.x version and trying the enable buttons but nothing came of it, I'll poke around some more later. Next up is checking out the pins under a microscope and resoldering it.

But that will have to wait

Hypothetically, if I swap in the same kind of esp32 from somewhere, should it work or does it need a very specific bootloader?

[mighty condor]

you can swap an esp32 ESP32-D0WDQ6 (should already come with a bootloader), flash it via uart with the right firmware and it should work.. granted nothing else is borked

[mighty pecan]

If all else fails I'll try that, might take a while to source one though

Thank you for the help, appreciate it a lot

[reef void]

The ESP32 bootloader is in the ROM on the chip. It's not possible to brick it.

If it's seeing the UART chip but nothing else then the internal power would likely be the issue as the UART chip is powered by the USB and then goes through a regulator for the other parts of the system.

[mighty condor]

oh yeah.. that's another possibility

so check the voltage output of the regulators..

[mighty pecan]

power seems fine, there's 3.3v on VDDA, VDD3P3, CHIP_PU, VDD3P3_CPU on the esp32

[mighty pecan]

The backpack chip seems to respond just fine, no reply from the esp32. Looks like I'll have to try to replace it once i can get my hands on one.

[mighty pecan]

I tried desoldering it and i'm having a hard time doing that. Din't manage to get it off without removing the heatsink from the pcb so far, but I plugged it in after reflowing the solder on the outside pins and it was actually alive for like 5 seconds. The oled was working and it even fired up wifi but died again shortly after

It's aliiive

I think i left a couple pins shorted last time so i went over them again with a load of flux and the soldering iron

So it seems like it was a bad solder joint all along? I'll post an update after some use

[mighty pecan]

two steps forward, one step back, it's only half alive now. After getting it back up I tried to reduce the tx power to the minimum and by accident bumped it up to 1W, It seemingly browned out over a couple seconds (sketchy power delivery?) and died again. Now it tries booting on power up but kinda shuts off afterwards. I managed to ping the esp32 while it was booting, but it looks like it's goes offline a couple seconds after powering up.

and it's completely dead again after some more attempts to power it up

I'll just toss the module into the spare parts drawer at this point i think, even if I managed to work it out it's way too much of a mission critical part to risk repeated random failures.

Sucks especially because it kinda sorta works when it feels like but also not really. Those are the worst.