I dont understand why would denter even fiddle with that battery...how the heck did he know battery was drained....why did he charged without asking you....he has messed up the wiring when reinstalling evrything back and wont even accept his fault even if you ask what/how he did, cause he didnt even know what he was doing....
As asked by Mujeeb above, pls mention ur city to guide u to better workshop for issue resolution.