Ahh so that's why my phone died. It was fine after first flashing it but didn't turn back on again after switching it off. Guess I had one of those bad chips (no way of checking now I guess as it's dead?)
Don't feel bad, you didn't know it was going to happen. the only reason I ever bought this phone was because of you having developed CM for it in the first place. Its been a good ride! On the plus side I'm getting a full refund from Tesco as they don't sell it anymore so might get a much better phone now for "free"!
I've had a similar experience today (assume my motherboard is dead) but doubt that the recovery or rom caused it, as other people have reported their G300's dying who haven't touched this at all. It seems that the hardware is kind of unreliable after a certain amount of time - people are reporting motherboards dying quite often now in the General forum.
Anyways.. yesterday I flashed the new recovery and new experimental CM rom with 3.4 kernel. It was working fine all afternoon and evening and then when I woke up this morning the phone is completely dead. Charging light won't come on, no response at all from the phone. I've changed battery, tried without any battery in it and just the charger, left it for ages etc, and nothing.
Its still under warranty so its getting a full refund (the retailer no longer sells them to replace it). I hope you can get yours fixed or replaced.