my iphone 4 isnt booting anymore after downgrading it to ios 5

I installed coolbooter and tried to downgrade my iphone 4 to ios 5, after it said to lock the phone i locked it and i saw glitching on the screen and it turned off, i thought it would turn on at some point but it wont.. Its not even in recovery/dfu mode which is weird.

btw originaly iphone 4 was on ios 7.0.4 so if anyone can help me or had the same problem before, please let me know. Thanks!