Hear the fans roar post SMC but no chime/no backlight/no keyboard
Two weeks ago, my macbook pro started to type out extra alphabets while typing on the inbuilt keyboard. I got an external iBall USB keyboard and noticed that when the battery was sufficiently or fully charged, the letter keys would type normally again. This worked out for a few days until a few of the keys became suddenly and totally obsolete. I continued using the external keyboard for my work. However, one day I put it to sleep and when I tried to use it again, the normal login screen showed up before going completely blank to never be turned on again. The screen basically appears to be turned off at all times.
My macbook is 5 years old now and has never really given me any trouble or has at least almost always positively responded to SMC resets and PRAM resets. Not this time though - when I do the SMC reset (using the built in keyboard) the light on the power cable changes for a few seconds, so I’m guessing the SMC circuit still works!?! Also, the light on the power cable seems to be working fine, so I guess the battery is charging alright. Except that when I long press the power key, I only hear the fans roar for varying durations each time and no other response. Nothing happens if I hit the Caps Lock key, so I guess hopefully this isn’t a display issue either. I am not sure what I can do at this point. Any guidance will be greatly appreciated!
I did recently move from a dry climate to a humid one but it is hard to swallow that as the reason for my Mac to act weird like this. Please help!!!!