(I'm an ASE Certified Technician) Are you putting it in gear and trying to drive? Does it it make any strange noises like grinding or clunking? Do the rear tires not move in drive as well as reverse? You've made sure that the emergency brake is off and there's nothing blocking the wheels from turning? If you said yes more than twice then you've got some issues. Could be anything from a stuck parking brake cable, damaged rear differential or axle or damage inside the transmission. I would need more info to narrow it down from there.
I've seen where people have upgraded the storage chips on some Apple devices but never with an Android. I'm sure it is physically possible with the correct module and the skill to actually do it without ruining your motherboard. The biggest challenge I believe would be finding a memory chip that is not only the same physical size and pinout but also is compatable on the firmware side as well. You're better off rooting the tablet and learning some tips and tricks on optimizing your ram management.
The most likely cause of your issue is a damaged Micro USB port. I have seen this issue from multiple different people including my own personal device. Insufficient support around the micro USB port allows for movement and subsequent damage to the port resulting in poor (if any) connection to the cable. I found that the only solution to this problem for myself, aside from replacing the port, was to put downward pressure on the cable (meaning push the cables connector away from the screen side of the device). This will work temporarily to charge the device. The only real solution I have found is to completely replace the micro USB port. Detailed instructions can be found here ( Remplacement du port Micro USB du Nvidia Shield Tablet K1 ). As for the short battery life, this is a direct result of the power and performance of the device itself and the need for a larger battery. You can thank Nvidia for that one (Lol). If you have rooted your device I would suggest using a kernel control app (I personally use...