I already got my Frearduino mega working again with Marlin installed.
Although it is working I have doubts about how I solved it if it was that way, I explain myself better:
The Frearduino 2560 + RAMPS 1.4 came originally with my Prusa i3 from HEPHESTOS, It has always been connected to my iMac using Mac software such as the Cura, Repetier Host and Arduino IDE; After It got looped I came to you for help and also I search into the Web for every tutorial about burn bootloader and all the information about it coincided in the same. At that point I was ready to buy a programmer on Amazon, but I decided to try the same procedure from Windows 7, so I mount a virtual machine on my iMac and I installed Windows 7 and Arduino IDE, connecting the cables from ICSP as suggested and IT WORKS!!! the first attempt it flashed the Bootloader perfectly; I disconnected it from the ICSP cables and I put the USB directly and I uploaded the Blink and it worked, then I went up to the Marlin sketch and its successfully uploaded too now it's like in its old days (All this from Windows 7 in my virtual machine), now I go out of Windows and I open the Arduino IDE and I goto Terminal and I see Frearduino working property but if I try to upload Marlin or Sketch but if I try to upload something simple like a Blink I get the same avrdude error: stk500v2_command (): command failed. It could be said that I have problems in Sierra (Mac operating system based on Unix) with the installation of the stk500v2 but I do the same operation with the Key Studio Mega 2560 board and it works great.
So far I can only upload sketch to Frearduino borard from Windows 7.
Any ideas?
Thanx in advanced