Linksys EA3500 versus Linksys EA3500 (Audi)?

Linksys EA3500 versus Linksys EA3500 (Audi)? I have 5 of the Linksys EA3500 routers, I was able to update the firmware on 4 of the 5, to 23.05.3 just fine. Well 1 of the 4 had a single flash fail, but re-flashing worked fine, from OEM firmware to factory 23.0.5.3. The issue of note is number 5.

Number 5 was at 19.07.7, and I was able to flash 19.07.10 without issue. But if I try to flash number 5 from 19.07.7 or 19.07.10 to anything higher, watching via the jTAG serial console, I get Verifying Checksum.... Bad Data CRC. I can recover back to the alternate firmware bank just fine. But after 7 attempts to flash ANYTHING creater than 19.07.x, the same bad data CRC.

Does this feel or seem like I might have a NAND (memory) issue? What is odd, is the OpenWRT database shows 'audi' support stops at 19.07.x, but non 'audi' EA3500 exists right up to 23.05.3. But I cannot seem to find anything via Google that itemizes 'audi' versus non 'audi' EA3500 routers?

If you have serial console access (not JTAG, that's something different), you should be able to see NAND read errors, if there are any. Likewise that should allow you to to:

  • check the u-boot evironment (printenv) for differences (bytes to load for the kernel)
  • try to load a modern initramfs image

I have a serial console... Not JTAG... why did I type JTAG. I did try to load the initramfs image for newer than 19.07.x, very version I tried failed. As I noted above, nothing passes the CRC check beyond 19.07.10. I validated the download of each image.

Watching the serial console, ultimately, with 23.x I get a kernel panic. Of the 5 devices 4, not issue, just the 1 is having issues, and it is the only one that 'defaults' into either an Audi>> prompt if bad CRC fail, or if it gets past that, I get a kernel panic.

Recovery to the existing 19.07.10 is consistent, and seems stable, just quite dated.