I hate to give you bad news after going through all that work because the driver swap came out beautifully. It sounds like the driver is shorting inside the pill causing the LEDs to burn up. You can try removing the driver and looking for the short or leaving it in and using a multimeter looking for a dead short to ground on the positive side but it sounds more like an intermittent short which is very difficult to find most likely happening due to expansion from heat or vibration and shock.
The other option is switching to a driver that fits the pill properly. These 2 drivers will fit with no modification and have 3 nicely spaced modes, pull 2.8 amps at 8.4 volts, have thermal protection and low voltage protection also.
I have modded a half dozen of these lights using the LCKLED driver. They recently went on sale at LCKLED they were the same price as the KD driver before. Also the KD driver has an older version of the micro contrller so the LCKLED one is a much better deal and they both are plug and play.
