I flashed a new rom it was working for a bit until the phone died on me. I tried accessing the recovery and download modes they work for a bit and then it turns off. Ive looked around and kind find any type of fix to this any help will be appreciated thanks!
It could be an overheat issue, or something else. Try turning the phone off, pulling the battery, wait a minute, then put it back in and see if that helps.
Does the battery have a good charge? There was a similar problem in another forum, and I think the reason the phone was shutting down so quickly was because the battery was nearly dead. Make sure the battery is charged to at least 25-30%, and try recovery again.