What to do when my phone (Moto e4) restarts by its own.

[Android Central Question]

I start having this problem for about less than 24 hours. Last night, around 12 am doing my work I decided to put a new micro sd (Lexar 64 gb uhs-1) then it was stuck at 30%. I keep restarting my phone and the same thing happens. Then, when I was about to press the power botton to open it up again, I accidentally press volume down. After a few minutes or so, I noticed my phone restarts by its own.
(I'm not sure what to do & please excuse my grammar :v - I'm still 15 yr)

 

[Rukbat]

Turn the phone off. Remove the SD card. If that clears it up, the card is defective. (Formatting the card might help, depending on the type of defect. If not, try to return the card and stick with SanDisk cards.)