HP EliteBook 840 G5 & G6

Problem Description	Symptoms	Solution	Source
Powers on but does not POST.		- Check for physical damage on trackpad/smartcard assembly. - Check power rails from ISL95338 (datasheets are publicly available.) - If none of the above leads to anything you may need to reprogram the BIOS IC.	Source
No power.		If using an aftermarket charger it’s highly likely it killed a mosfet.	Source