8250 battery problem... a bit strange

Hello :)
I am a hardware guy, but here i am lost in a harware issue.
Regarding my boss's 8250, he was all the time (over a year) using a non-original battery, Li-Ion with 850 mAh. Now this battery got worn, it have to be charged every day. I replaced it with a original Nokia BLB-2 battery, and it did not work (showed full battery, but the phone turned off after about a minute. It could be turned on again immediatly only to repeat this "cycle"). As the battery was brand new, i had it replaced in the Nokia-Shop, but strange, the second one (also original BLB-2, and i saw the seller changing it, he did not give me my "old" one again)behaves the same.
Now, i tried to "deforming" the contact pins of the phone a little, making them having more pressure against the battery's contacts, cleaned both those phone pins and the battery contacts, charged the battery full in a desk charger and tested it several times. It's always the same: Phone powers on, finds network, and goes idle. Shows all four battery bars. Then, after about one minute, it simply turns off. Netmonitor test 23 shows at all the time (also while charging) a battery temperature of -15 degree centigrade. And test 20 shows "LiAFu" all the time when charging. But there is no further error message such as "not charging" or whatever, it charges normally, and during charging, the phone won't shut off.
What could this be? When putting back the old, non-original battery, everything is fine. Can he phone be "spoiled" by this battery?
Please, someone advice me... thanks a lot!
your Thanh