Trackpad and Keyboard stopped working; Can do a SMC reset though

Everything was working perfectly until two weeks ago, I went to a event which was taking place in the open and I had to open my Macbook where it was dusty and sunny. My Mac was in my bag all the time, and so it's also possible that it might have endured some movement.

Now, around 5 days ago, I opened my Mac and all of a sudden I can't move the trackpad and can't type in my password because the keyboard doesn't work. So, I didn't use the Mac at the event any more.

I came back from the event two days ago and tried resetting SMC which worked, but resetting NVRAM and PRAM didn't work, same with boot options (pressing Shift for Safe mode etc.). Connecting an external keyboard worked, but resetting NVRAM using the external keyboard and booting into safe mode didn't solve the issue.

Can anyone tell me what the issue could be? Please let me know if I should give any other information.

Here is the CoconutBattery screenshot. Having said that, let me mention the following points:

1) My original charger’s cable connector became loose (the part which connects to the macbook) and I had to hold it up for charging. Soon, it stopped working, signalling an issue in the cable. So, I bought a replacement charger by FUGEN instead of the original charger 1.5 years ago. This could have led to an issue in the battery, as you say.

2) Around 1 month ago I started receiving a message to Service the battery (like this: https://goo.gl/images/urW2EY). It’s not showing now, though. My battery life has deteriorated considerably too, running 3-4 hours at max on full charge, and rapidly discharging even in normal use.