Electrical issue causing battery to drain

Hello all, I have a 2013 Honda odyssey and know next to nothing about cars, so I was just hoping for an estimate for when I take it to a mechanic and avoiding unnecessarily expensive work etc.

My primary issue has become noticeable over the past 4 months where an electrical issue is causing the battery to be drained to the point where it needs to be jump-started if too much time elapses between starts/drives. Progressively with colder temperatures (and perhaps weakening of battery and/or starter/alternator) it is now down to about 12-13 hours but the car struggles with signs of weak battery by that point. No noticeable issue if driven within 8 hours. I know it was bad for battery/alternator/starter to put it off, but in these few months, the car has been jumpstarted maybe 10-12 times. I know it’s not a bad battery (at least not originally and not the root cause) because the battery is new (about a year old).

Apparently this is due to a door/trunk not properly being closed, stemming from a minor accident years ago. [there is a long dent on the side adjacent the trunk and on the driver door from being slightly crunched against garage parking pillar. However it’s been years since without any issues]. But for some reason it’s become problematic in recent months. Earlier this year before realizing any connection, the car would indicated through sound that the trunk was not closed properly. A constant droning alarm sound for ‘door not closed’ would sound continuously for the trunk (despite the dashboard diagram not showing trunk or any door open). Sound could be stopped if I turned auto door setting off, re-close trunk and turn auto doors on. The first time I managed to re-shut the trunk and could drive with auto doors on, but then the last time trunk was opened I couldn’t get the alarm to stop, so I just turned off auto doors. After a few weeks driving with the auto doors setting off, toggling auto doors on/off now did not produce and still does not produce an alarm sound for open door. No dashboard sensors/sounds indicate a problem throughout this time. Driving with auto doors off has had no effect on battery life. I don’t understand why this issue would emerge after years without issue?

Can the sensor be deactivated/disconnected? Or is there something else that can be done inexpensively? I would rather avoid expensive body repair work if possible.

Lastly, this metal piece has sometimes been scrapping when I drive. Picture taken from under driver side door: www.imgur.com/a/X4DPduK … Can this just be screwed back on?

Since the last time I tried to jump was unsuccessful and the turning sound seemed absent (I think), I am worried I may have pushed the car too far and may need a new starter. I will update when I try to jump in a few hours. In this case, a quick google search says a new starter replacement should cost between $350-550 including labor. Is this fair and if I haven’t made any incorrect statments, how much more should I expect to pay a simple sensor disconnection fix for the battery? Is this something that all professional mechanics know how to do?

Thank you for reading and thanks in advance for your help.

First off… we don’t know where you live so you could be paying $175 a shop hour or $65 depending on where you live. You don’t have to use the dealer but the shop should be one that can do real diagnostics, not just swap parts.

A parasitic draw test takes some time to perform and the mechanic needs to be paid for their time. Figure roughly $200 and go from there. Don’t speculate on the cost, I won’t. Until the cause is known, the cost of the repair is unknown. Once the cause is found, the bill will go up from there.

Ignore the cost of a starter for now. Likely you have not done it any harm.

Have the part dragging - I don’t follow picture links - re-attached. Let the mechanic do his job and fix it.