I have had this more than a few times , once it was a done in battery , once it was a slight kink in the hose way back on the reel , i unwound it all off let it pressure up and it sorted itself out , once it was blocked strainers and once it was due to using hoselocs with the built in waterstops , i knocked them out and all was good .
Just a few things to look at before you buy a battery or rip the wiring out !