Pi 4 mouse and keyboard problem

Hi all
just started to set up a pi 4 last night from the little bird kit.
all went well until we set up the wifi password and pressed enter.
just after that the screen went blank.
we waited then after some time we switched the power off and then back on
we then had the set up page on the screen but the mouse and keyboard
won’t work.
we tried other mouses and keyboards but no luck
the mouse curser is just stuck on the screen
can anyone help please ?
thank you

Have you plugged in the dongle?