the battery will work.
Now a signal component can be the fallowing:
- Signal wire connector(you can broke it from the board if you do not remove the wire with caution)
- The actual signal wire(you cannot take it from the 2i the(it is smaller)
- The charging dock(the bottom board) (you cannot take it from the 2i, they are different, but quite cheap)
If the repair guy didn't mess the first 2 then the charging dock should be the issue
Here is the charging dock: