This just started happening to me a couple days ago, after having my S9 in a damp swimsuit pocket. I've taken this phone in pool many times over the past year, so it is odd if that was the culprit or just coincidence. Like the other users here, I first tried safemode, clearing cache, and factory reset.
Thanks to Terri, disabling the fingerprint unlock option is a workaround to the phone powering off when locked. However, I have several apps (Venmo) than I cannot use now since when they first prompt for my fingerprint, the phone shuts off again. I'm thinking I will have to reinstall these apps now.
Dear Samsung, is this a hardware or software issue? Can you replace the fingerprint sensor for us or release a patch to fix this problem?
@qballistic can I please have your full model number, baseband version, and service provider?
@qballistic Thank you for that information. If the device still shuts down while in safe mode and a full factory reset hasn't resolved it I would recommend a service repair on the device. Would you mind sending us a private message with your IMEI number so that we can look into what options you have?
So my S9 Plus began doing this about 4 days ago. My phone is in perfect condition never being out of its otterbox case since it went from the box to the case while still in the store. After doing a Cache clear, running in safe mode and doing a factory reset, samsung tells me I have to pay and send my phone in to be fixed without a replacement device while mine is repaired??? oh yeah Warranty just expired on 5/22/19. I notice that once it enters sleep mode the white lightning bolt on black screen appears and the phone shuts down and usually reboots, this happens no matter what battery percentage I am at. The phone works fine as long as I am actively using it, but once it goes into sleep mode it shuts off completely.
I had the same problem with my phone. All my carrier did was keep sending me a replacement phone. After I did my own research it turns out I had a corrupted file somewhere in my SD. Since all my photos and videos were already on the cloud. I toss the SD card I had, got a new one and haven't had problems since.
This one happened to me before because of overused space on Ram or software not properly installed.. I would suggest you back up and factory reset...the factory reset is the best tune up for the phone ive tried and works well with my phone
Good morning. This exact problem started happening to me this morning. Any time the screen went off, the phone would not respond and I would have to turn it back on. I disabled the fingerprint authentication and that fixed the issue. So, is this a hardware or software bug? What can be done to fix it, so I can use the fingerprint authentication again? @SamsungAdam