Released in 2015, the HP EliteBook 850 G2 is an update to the 850 G1, featuring newer processors and an optional touchscreen. Repair guides and detailed information can be found here.
This behavior usually points to a hardware power or motherboard issue. Since the keyboard backlight flashes briefly and the fan spins, the laptop is receiving power but failing POST. Try a hard reset first: unplug charger, remove battery, hold the power button for 30–40 seconds, then retry with charger only. Reseat RAM, SSD, and display cable. Test with one RAM stick if possible. If there’s no display even on an external monitor, the issue is likely a faulty motherboard, BIOS corruption, or power IC. In that case, professional repair or board replacement is required.
Mine did this after the battery died. Wouldn’t turn on with or without the battery, just flashed the keyboard lights. CMOS reset fixed it. Pulled the battery, held power button for ~30 seconds, then tried again.
@dynamicrex does the fan spin normal, fast or just a little bit? What have you already checked?
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
Fast spining fan
crwdns2934271:0crwdnd2934271:0 Dynamic Rex crwdne2934271:0
Please Remove the RAM and check
crwdns2934271:0crwdnd2934271:0 Mr.Hisham crwdne2934271:0
@dynamicrex Have you attempted to remove/reinsert the hard drive in addition to the RAM?
crwdns2934271:0crwdnd2934271:0 teardown-er crwdne2934271:0