Your preamp is the active EQ part of your bass. It's the reason you claim to have booming low end (normally) and an increased output signal. Active electronics rely on a power source (the 9V you put into your battery slot) to increase the output of your bass (hotter or louder signal) and also have active EQ functionality (I believe there is at least bass and treble 2-band EQ knobs on the Schecter).
Essentially, what could've happened is a surge that fried the preamp of your bass, making your active electronics kaput (assuming it wasn't shoddily connected in the first place).
Three things you can do:
1. (If you haven't already) Replace the battery with a new one - just to make absolute sure it wasn't the power source that was bad
2. Take it to a tech and be prepared for a replacement preamp. Unless you are familiar with electronics and soldering, you will need a professional to help you out.
3. Accept that you can only play it in passive mode (as it looks like the bridge pickup is a passive pickup). Being in the bridge position, you'll find the pickup will give you a more mid and treble forward tone, and lack the signal output that you liked with active electronics.
EDIT: Just reread OP. You've tried different batteries, so that leaves you with two options.