RE: Trying not to get discouraged, but...
Do the interior lamps flash on and off randomly, or is it more like a turn signal? If so, it sounds like the BCM is not configured properly, and that is likely why the TPMS lamp stays on.
When testing for a battery draw, after connecting the ampmeter in series, it is normal to see a draw of about .5 amps. Wait approx 40 minutes without disturbing the meter or connections. It will take this long for all modules to "go to sleep". At this point, the draw should not exceed .05 amps (50 milliamps)
