Nevermind I fixed think my OS version was not made for the 3b+. If you are having this issue, beware that the red led flash might not come from a power issue but an os compatibility issue.

HI, so I am having a problem with my new RPI3b+, it worked a few days normally but then (after a few days inactive) I tried installing recallbox (with etcher on ubuntu 17.10) to play games, but I wouldn't boot (red light flashing, no green light). So I thought it might be a power supply issue, so I ...