Why does my A21s screen flash white for a split second when i try to boot it up?

[Android Central Question]

Last night, I was using my Galaxy A21s just fine when suddenly the Samsung logo appeared and my phone died. Completely normal since I got a 5% warning a while ago but just forgot about it. I plug it in the charger and wait a few seconds to power it on again but when I do the screen flashes white for a moment after holding down the power button for a couple secs and goes back to a black screen. If I tap the power button the exact same thing happens after a couple secs and goes black. If I hold down the force restart buttons, the screen will flash white every few seconds until I let go. I spent over an hour last night trying several fixes several times for similar cases but nothing worked. This is a brand new phone that's less than a month old. I've only found one person with the same problem but they have a much older phone and their case was slightly different.

 

[spARTacus]

I am trying to see if I can reproduce this. What do you mean when you say "...if I hold down the force restart buttons" and when you say "...if I tap the power button"? I must not be doing exactly what you are doing, or not noticing what you are noticing.

 

[B. Diddy]

Welcome to Android Central! It sounds like it could be either a battery failure or a motherboard failure.

Keep the phone plugged into a wall outlet for at least 6 hours undisturbed, then try powering on again by pressing and holding Power for at least 15 seconds. If the flash keeps happening, then see if you can boot into Recovery Mode and either wipe the cache partition or do a factory reset: https://www.hardreset.info/devices/samsung/samsung-galaxy-a21s/. If you can't, then it's probably a hardware failure. Is the phone still under warranty?

Please register on this forum, which will allow you to engage in discussion more easily, as well as post images. https://forums.androidcentral.com/ask-question/409154-join-android-central-community.html

 

[spARTacus]

Some of those instructions seem to suggest how to bypass security credentials and such. Is that ok?

 

[mustang7757]

Try charging it through USB of a computer for a few hours and then see if it responds sometimes when battery turns abruptly when 5% it needs that slow steady charge

 

[B. Diddy]

Some of those instructions seem to suggest how to bypass security credentials and such. Is that ok?

That site does mention some methods to try to bypass FRP (which we don't condone here), but in general the site is handy for the steps on how to get to Recovery. This shouldn't be an issue for you anyway, assuming this is and always has been your phone.

 

[spARTacus]

Yeah it's not an issue for me, I am not the OP, my phone has indeed always been mine, and it will also always remain in my physical security possession.