I was also able to reproduce the fast flashing power light by then performing a TFTP flash to factory firmware. Based on the above, I believe that going from stock firmware to DD-WRT with firmware other than r42954 (or r44715) causes the nvram_cfe to become corrupt. I am considering ...
1f05 64 mtdblock5 (driver?) Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,2) CPU1: stopping When I am trying to send stock firmware or ddwrt firmware via tftf i see this: Quote: Reading 192.168.0.66:ArcherC9v1_tp_recovery.bin: Done. 14381945 ...
https://dd-wrt.com/support/other-downloads/?path=betas%2F2019%2F09-13-2019-r41027%2Ftplink_archer-c9v1%2F Thanks a lot. I tried installing it, but having 5... error, so use the testing TP-Link firmware as suggested and I'm now on r41027. Next step is make it as access point...