Check your entire switch matrix for ghost activations, it is possible you damaged the U20 integrated circuit on the MPU.
Next you have to test your entire lamp matrix and note deviations or incorrect lighting so you can further troubleshoot.
This is making the assumption you already reseparated the gun handles on DM so you do not have the continuing short.
Shrink wrap tube please, no electrical tape.
Buy multiple sizes, it is not that expensive.
Do repairs correctly.