Will be a hardware issue; I would order and try a trackpad and cable to test it with. Inspect both sides of the logic board for liquid damage first, and also the battery PCB, before ordering the parts. If you have a multimeter to hand, I would suggest first measuring PP3V3_S4 (get a schematic and board view for 820-4924), since this is the voltage going to the trackpad enabling haptic feedback to work. This is also a power rail present in hibernation, and may be low/missing, causing the MacBook to completely turn off when it goes into a deep sleep (asleep for over a minute), causing the other issue you mention.
I would inspect, measure the voltage, then order the parts. No way of determining the cause without trying test parts unfortunately