R7800 -> Flashing openwrt causes bootloop (bad block in kernel area)

Here to say that I believe I'm in the same unfortunate boat.

Just received a new R7800 today, and any flash attempt results in a boot loop. I can successfully go back to the vendor R7800-V1.0.2.68.img, but haven't managed to successfully flash OpenWrt yet (despite years of doing so on other equipment).

Should I be looking to just get another R7800, and maybe it won't have any of the same bad blocks?

I've read through all the related threads I can find on this. Did I miss any options for confirming the bad blocks, and/or successfully flashing OpenWrt - without opening the case (and violating the warranty / options for return)? Are there any custom builds I could try over TFTP (no serial or JTAG) that would overcome this?

This was intended to replace my TP-Link AC1750 / Archer C7 V2, on which I cannot rely upon stable wireless connections (Archer C7 2.4 GHz wireless dies in 24~48 hours, Archer C7 V2 - Massive Problems). If anyone has any better recommendations for similar hardware that is well-supported under OpenWrt, please share...