Reflowing isn’t very difficult even with a basic hot plate or frying pan, though the Lumintop MCPCBs have a rather soft mask. You’ll probably want some solder paste. If you’re talking about 219B, flashing the firmware to a lower output version allows you to safely use any cell you want, but as long as you stick to lower current cells like NCR18650GA the stock firmware works ok. You don’t need to change anything for 219C.

However… the seller should be sending you the correct light, express, or providing a partial refund. Two wrong lights in a row is unacceptable. The knurling damage is also rather unfortunate.