hot bed problem light blinks then nothing ?

[spart]

hi all, just set up rambo board i turn the hot bed on to test it and all i get is a sound like its going to power up the light on hotbed blinks once then nothing. turned up power supply thinking i was under power iam now set to 12.40 but did not help
{ thought it might be to much for the board, hope not so turned it back down to 12.24 }
power supply gets to dam hot as is should just put that under the glass lol,

hotbed first,

any one know what could be going on with this hotbed


everything else works great other then hot end wont power up all so but get to that after

[Broose]

The firmware won't let the bed heat up unless you have the hotend working correctly. Get that going first and then see if your bed will heat up.