Help with bricked CPE510

Hi folks, I would appreciate any advice that might have. Long-time openwrt user/tinkerier, but no experience with serial.

So I have 2 TP-LINK CPE510 units (these are the 5ghz outdoor units with the built in directional antenna). I needed to restore them back to stock firmware to take advantage of some of the features of stock firmware not offered in OpenWRT (specifically there is a TDMA-based linking option that makes 2 of these units not compatible with standard wifi protocols, but creates a solid bridge using 2 of the devices.

Anyways, one of the units was able to flash back to stock with minimal issues using the documented procedures in the WIKI (use tftp server with recovery.bin, hold down reset button while powering on device, and after a short time, it pulls recovery.bin from tftp and flashes itself).

So the first unit successfully flashed back to stock.

The 2nd unit, however, just would not cooperate. It would successfully request and download the recovery.bin from tftp, but when it would reboot, it would still be on openwrt. I tried this dozens of times with the same result. It was crazy. I tried different versions of the stock firmware with the same result - always back to openwrt.

So I decided to attempt to flash to stock from openwrt using mtd. I stripped the header from the stock firmware bin, copied it to /tmp/ and used mtd to flash. mtd -r write /tmp/original_firmware.bin firmware

It appeared to be successful, but upon reboot, all 7 leds just stay solid green and nothing happens. I can still attempt the recovery procedure by holding in the reset button while powering on, and the devices DOES still download recovery.bin via tftp, but after a short time it goes back to having all 7 leds solid green again.

Trying to flash the openwrt firmware by naming it recovery.bin and serving via tftp results in the same....so it appears that my mtd fiasco has managed to brick the unit.

Any suggestions or advice?

TIA

Any ideas?