Arduino doesn't turn on please help

hey guys, i'm 15 , i'm quite new arduino. board have arduino mega 2560 r3. has been working fine years now. embarked on new project, robot rc car inspire project : http://www.instructables.com/id/james-your-first-arduino-robot/ . plugged prototyping shield on arduino , started wiring, while board plugged computer. sensed stopped working. green light turned off. touched board , 501v chip near usb input hot. think smd component fuse (the 501v chip). plugged board moms computer , worked moment , stopped again, , once more 501v chip extremely hot. plugged in 9 volt batter dc power input, still didn't work. i'm helpless friends. please me if possible.

we need circuit diagram how connected. please disconnect connection ; upload simple blink example check working. make ensure nothing being connected.

now check whether ic gets heats or not. if not getting heats means board under working condition ; if heating means destroyed usb ttl converter ic  .need time replace

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