Very surprised that an Ibanez was in that bad condition - especially for the RG series, which are still (afaik) produced in Japan. DEFINITELY write to their customer service and explain the situation. Send photos of everything.
Here's a sample letter for you to write to customer service.
Subject: Extremely Disappointing Quality Issues with New Ibanez RG421
To whom it may concern,
I am writing to express my deep dissatisfaction with the condition of a recently purchased Ibanez RG421 guitar. As a long-time admirer of the brand, I was shocked to discover that this instrument arrived in noticeably worse condition than even your most affordable models.
Upon inspection, I found the frets to be visibly corroded, and the guitar exhibited persistent fret buzz—even after the neck relief had been fully adjusted with no further room for correction. Additionally, the truss rod cover was installed backwards, indicating a clear lapse in basic quality control.
This is not the level of craftsmanship or attention to detail that customers expect from Ibanez, and I am extremely disappointed. I trusted the brand’s longstanding reputation for quality and reliability, and this experience has undermined that confidence.
I ask that you address this issue promptly and advise me on the next steps to obtain a properly inspected and fully functional instrument. I expect a resolution that reflects the standards Ibanez claims to uphold.
Sincerely,
[Your Name]