Mytouch Slide won't fully turn on.

[p10]

My brother had a Mytouch Slide 3G, but had switched over to At&t and decided to give me his Mytouch. The phone worked fine for about a week with few problems. Then when I locked it and tried to unlock it the screen stayed black. I took out the battery and waited about thirty seconds and put it back in. When I powered it on the phone stayed at the screen stayed at the very first screen where it says T-Mobile Mytouch Slide. I plugged it into the charger thinking maybe it would help in some way. So I turned it off (via battery taken out) and turned it on again with the charger in. This time it turned all the way on, but where it asked me for the code to unlock my sim was now the problem. The screen looked like it was flying upwards, stopping at some points then continuing. I don't know what's wrong. Any help is appreciated.