Makerbot #453 : Motherboard not working part2

I was unable to program the motherboard.

I only need to push a bootloader first, but no AVR programer here :-(

I found a way to do it with my TTL cable as describe here :

http://exmrclean.blogspot.com/2009/05/burning-avr-boot-loader-with-usb-ttl.html

Only diff, I used the ATmegaBOOT_644P.hex (the one with the P ).