Fastboot mode means that you're in the bootloader interface. The lock status refers to the bootloader's lock state, with your's being locked. Unless you plan to root your device or flash custom software, it's in your best interest to leave it locked. The fact that simply holding the power button and it boots into that mode seems to indicate that you're volume buttons are both being read as pressed. If you're doing that, then if you don't the tablet would boot up normally.