Cannot install apps on thinkpad tablet (android)

[Soul Samurai]

Apologies if this is the wrong forum for this. I recently purchased a secondhand Lenovo Thinkpad android tablet (model 1838-25U). It came with the Android 4.0.3 set to factory settings I believe. Unfortunately the Play Store doesn't seem to work; I registered a new gmail account and after registration completed the application crashed. I launched it again and entered my new account details, and it crashed again. Now every time I try to launch it, it just comes up with a message saying "Unfortunately Google Play Store has stopped".

I tried to install apks from an SD card, but I can't seem to figure out how; the only file manager I've found on the device (USB file copy utility) doesn't really give me any options except for copying files around. I tried to update the OS, but I just get a message saying "Not connected to file transfer server".

Does anyone have any idea what could be wrong with the tablet and how I could fix it?

On a side note, I've recently discovered that there are alternate tablet operating systems to Android/Windows/whatever the iPad runs, I'm curious about whether anyone's tried anything else on the Thinkpad Tablet, and how well that's worked out?