Why will my Chomebook not re-boot after successful recovery procedure?

Chromebook would not boot up......screen blank......hooked HDMI out to TV and could see very faint image of desktop background. Finally screen popped up with message that OS was needing complete recovery. Tried unsuccessfully twice with 2 different thumb drives...finally worked successfully when I used a SD card. Says "Recovery successful, now remove recovery usb and your computer will re-boot" But it does not re-boot...screen goes black and stays that way......is this a hardware issue?