How the key got stuck? Sugary liquid spill perhaps? BTW any liquid spill is not covered by manufacturer's warranty.
Try to remove hdd, odd, memory. Plug AC adapter but not the battery. Make sure AC adapter is good. See if it gives beep sound. If no beeps, no screen, try different AC adapter (an universal one is ok). If still no beeps or display, then probably mobo is bad. Need to take to a repair shop.
Starting disassembly but stopped. I suspect mobo also as unit won't do anything. May try to replace mobo but unit is > 5 yrs old so may not be $$ wise to repair. Thanks for feedback.