The older firmware(1.5.7 & 1.6.8) allows for ftp access. Through ftp access you can gain access to the internal file system which allows for certain mods like increasing transmit power and opening telnet access. Telnet access gives you the ability to access certain internal programs that allow...
The procedure is exactly as described above.
Follow the 1.8.10 downgrade procedure found here.
If you haven't already done so, download the zero bite debug files found at the top of this post and extract the zip file. Locate the debug file for the P3S (P3C_FW_DEBUG.bin).
Transfer that file to...
Confirmed! This works as described. I successfully downgraded from 1.8.10 to 1.6.8. I downgraded first to 1.7.9 then followed the same process down to 1.6.8. Great post! Thanks!