DVR recovery via Putty + TFTP

I have a Dahua NVR5416-16P-4KS2 DVR

After upgrading to DH_NVR5XXX-4KS2_MultiLang_V4.002.0000000.6.R.221115 from this site : https://www.dahuasecurity.com/products/All-Products/Network-Recorders/Pro-Series/NVR5-Series/4HDD/NVR541654325464-16P-4KS2E

using the flash drive the recorder does not want to start despite the fact that theoretically, the installation was successful.

The recorder starts, the screen shows as if the system is loading, but after a while it resets, and so on and so forth.

I have read that I need to connect using the serial port and upload the firmware again via TFTP, according to the instructions I found on this site:

https://ipcamtalk.com/threads/dahua-ipc-easy-unbricking-recovery-over-tftp.17189/

Unfortunately the only stage I reached was connecting via serial 232 via Putty. I can see the data displayed at startup and I can stop the bot, then I die out.

I'm looking for someone to help me get through this firmware installation so I can regain DVR functionality.