Mega 2560 very hot

Hello every body.
i have a arduino mega 2560 R3 for my project , it works very well for 1 month ( i power it with usb) but today it isn't work and mega 2560 micro controller is very very very hot at a few second.

note: Regulator is not hot at all
ON,L,TX,RX, LEDs are on!!!!
I disconnect every thing form the board and only connect board via usb to my PC.

(deleted)

If the microcontroller itself is hot, it's dead. Throw it out and get a new one.

Investigate your hardware design (maybe post it here?) to try to determine what could have damaged the chip. The AVRs (except the ones with native USB, judging by posts here) are pretty resilient, and most insults will blow pins, but not cause the whole chip to get "very very hot". There is likely other damage to the board as well from whatever event killed it.

zed71220:
OMG !!

Yes, it is most likely dead or fatally damaged. You can cool it down and see if it revives, but even if it does, it's suspect.

Check your circuit for something that may have happened to it. The only times I have ever had a microcontroller chip emulate a heating coil, it was because of some power problem - too much voltage or reversed voltage.