My jailbroken iphone is stuck on a blank screen not a boot loop?

It is just a blank screen and i can't hook it up to my computer because it has a passcode lock which i can't reach because the phone is blank. I opened cydia and it wouldnt open so i locked the phone trying to fix it, hoping to lock and unlock to help. It just stayed on a black screen. Still vibrates saying charging but no screen response

Have you tried hard reset? ( home button + power button for 5-10 seconds )

if that doesn't work try this.

THIS WILL WIPE PHONE
power phone off (if can't do this, only thing I can think of is do hard reset to power phone off or let die)
HOLD HOME BUTTON as you plug in cable via usb, DO NOT RELEASE home button UNTIL "Cable + BLUE apple sign" appear, then release, and follow the instructions in itunes

First of all… NEVER Jailbreak an iPhone!
Try resetting… Like factory reset… That might be your only option!