DeletedUser29 If you want the data back, honestly I would suggest engaging a professional who knows how to do that. It may or may not be "gone", but clearly some hardware intervention by a skilled technician will be required.
If you don't want the data back but wish to reduce the likelihood anybody can ever get it (which might be appropriate if you'd been using a shorter PIN or passphrase), I would suggest literally chilling the device (refrigerator for several hours) in case what's causing it to shut down is a cooling problem, then quickly entering Recovery and triggering a factory reset. If that's not enough assurance, you might remove and incinerate the flash storage.
What to do depends on what you want to achieve. Based on the description, I am unaware of something simple that would improve the situation. If you do want the data, I would recommend against turning the device on except under the direction of a skilled technician.