The battery may have failed.
If there is detectable rear cover or display bulging that's a telltale indicator of a battery failure.
Do not attempt to charge if so.
Batteries can fail with no detectable swelling.
Try hooking up the charger, anything?
Disconnect if still dead; may or may not be a battery failure.
Was the phone at less than 40% when it died?
If it responds to the charger allow to charge for a few minutes and try to get it to boot.
If it boots you likely have a battery failure, disconnect the charger and replace the battery asap. Do not use it until you do.