phone dies in 5 minutes after charge

hello,

I've searched and could not find a answer.

This problem started about 3 months ago. After a full charge i would unplug and start my phone and it would keep restarting for about 5 hours or so. Now the problem is after a full charge I would start it up, it will boot up fine with no problem. Within 5 minutes of usage, my phone shuts off. I'll turn it back on and sometimes it shows i have 50% battery life left, most of the time no more battery life left.


Do i need to replace the battery or the phone?

TIA..

It was reset twice at the sprint store.

It's more likely a problem with the battery than with your phone.  I had a similar issue, but mine lasted just a few more minutes even when the battery in android indicated that it was full.  I exchanged my evo4g at Best Buy for another one but I had to keep my old battery.  Then with the "new/refrb" phone and same old battery I had the same issue.  I got a new battery at amazon and the annoying issue went away. (I got an extended battery B0042TY68C that now lasts me 8+ hrs with regular use).