Hola , esto es lo que me sale:
avrdude-slic3r -v -p atmega2560 -c wiring -P COM12 -b 115200 -D -U flash:w:0:C:\Users\dioni\Desktop\PRUSA\prusa3d_fw_MK3S_3_9_0_3421.hex:i
avrdude-slic3r: Version 6.3-20160220-prusa3d, compiled on Mar 21 2020 at 12:45:57
Copyright © 2000-2005 Brian Dean,
http://www.bdmicro.com/
Copyright © 2007-2014 Joerg Wunsch
Using Port : COM12
Using Programmer : wiring
Overriding Baud Rate : 115200
AVR Part : ATmega2560
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PA0
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
eeprom 65 10 8 0 no 4096 8 0 9000 9000 0x00 0x00
flash 65 10 256 0 yes 262144 256 1024 4500 4500 0x00 0x00
lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
Programmer Type : Wiring
Description : Wiring
Programmer Model: AVRISP
Hardware Version: 15
Firmware Version Master : 2.10
Vtarget : 0.0 V
SCK period : 0.1 us
avrdude-slic3r: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.01s
avrdude-slic3r: Device signature = 0x1e9801 (probably m2560)
avrdude-slic3r: safemode: hfuse reads as D8
avrdude-slic3r: safemode: efuse reads as FD
avrdude-slic3r: reading input file "C:\Users\dioni\Desktop\PRUSA\prusa3d_fw_MK3S_3_9_0_3421.hex"
avrdude-slic3r: writing flash (248818 bytes):
Writing | ###################avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x13
avrdude-slic3r: stk500v2_paged_write: write command failed
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x14
avrdude-slic3r: stk500v2_paged_load: read command failed
***failed;
############################### | 100% 70.78s
avrdude-slic3r: failed to write flash memory, rc=-1
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x18
avrdude-slic3r: stk500isp_read_byte(): timeout/error communicating with programmer
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x18
avrdude-slic3r: stk500isp_read_byte(): timeout/error communicating with programmer
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x18
avrdude-slic3r: stk500isp_read_byte(): timeout/error communicating with programmer
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x18
avrdude-slic3r: stk500isp_read_byte(): timeout/error communicating with programmer
avrdude-slic3r: safemode: Sorry, reading back fuses was unreliable. I have given up and exited programming mode
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_recv(): timeout
avrdude-slic3r: stk500v2_getsync(): timeout communicating with programmer
avrdude-slic3r: stk500v2_command(): failed miserably to execute command 0x11
avrdude-slic3r: stk500v2_disable(): failed to leave programming mode
avrdude-slic3r done. Thank you.