MacBook Pro 17" 2009 doesn't power on even after keyboard replacement
I've just decided to replace my keyboard since some keys don't work anymore. For this, I had to disassemble it. I've spent a long time trying to connect the keyboard flat ribbon and after finished, I'd power it on and it powered on normally. I turn it off in order to replace the back cover. When I've tried to turn it on, it didn't work anymore. No lights, no fans but the battery was still charging. I've decided to use the power pads to power it on and it works. I've then imagined being the new keyboard and I reconnected the old one. Surprisingly, it still didn't work. What could have been happened? Could somebody help me?