iPhone isn't recognized by Itunes & 3utools

Hello. Another problem again. This time it has to do with software issues. I got two iPhone 6s, and I’ve semi-flashed it once, until the computer couldn’t handle the ram requirements and stopped midway. So I’ve gotten a new computer with 8 gigs of ram and plugged the phone into the computer. Problem here is that it couldn’t recognize the phone despite being in recovery, so I put it in DFU. Same results, but this time the phone itself went dead. No sign of life on this side of the planet.

It’s not an issue with the cable or the computer. I recently flashed a 6s with it and the cable I’m using is genuine Apple. You guys know what went wrong here?