Iphone 5s dies when I release home button

[mnm54312]

I bought a broken iPhone 5s for really cheap, it was stuck in a boot loop. After it died I plugged it in, couldn't get anything for awhile..eventually I got it to turn on by plugging it in and holding the home button. Now, everytime I do that it loops 2 or three times then stays on the 'connect to itunes' screen. But as soon as I let go of the home button it dies. Any ideas on what to do?

 

[MaxSmarties]

Have it serviced.
Sorry about that, but it clearly is defective and it probably is the main board