recovery mode loop. Cannot solve

Bought an iphone first gen 4 gb from some guy on craigslist for 80 bucks for the intention of fixing it and reselling it. This is what i do with electronics. I can fix pretty much everything but for the life of me cannot figure this problem out. When you turn the iphone on it goes to a pineapple then to a steve jobs cartoon. Neither my pc nor a mac will recognize it. Also i cannot get it into dfu mode. I have tried manual methods, a command line method, and i have tried using irecovery which is another command line method. It will not even see the iphone. My computer does not even make a connect sound when i plug the iphone in. I have also tried two different cables. After i keep the iphone on the steve jobs cartoon the iphone shuts off and then boot loops. Any ideas?

The Steve Jobs swearing in Cyrillic cartoon is indicative of an earlier jailbreak on the device, and not really much more than that. If you're not getting connectivity over USB, it's likely a hardware problem -- does the phone charge when you plug it in?

If the home/power DFU mode method didn't work and the iRecovery DFU mode methods didn't work, I'm not sure what your options are other than to figure out if it's the connector that's broken. That said, iRecovery will only work if the USB connection is valid, so if you're not getting connection when you plug it in, the first thing you need to do is figure that problem out because nothing other than the home/power will work on the device to get it to DFU mode if you don't have that USB connectivity.