How can I tell if my Samsung galaxy tab s 10.5 has restarted?

[el_caro]

I have had issues with this tablet since new- not charging, random frequent spontaneous restarts and an occasional lock up in the on state . It was repaired under warranty but shortly after end of warranty problem reoccurred. Was going to bin it the other day but decided to have another shot at fixing it.
Performed factory reset. Problem still persisted.
While playing with everything after it locked up and would do nothing but show both buttons lit up, I decided to remove the micro SD card. Instantly it came to life again.

It seems with the card in the problems described above continue but with the card removed it seems to function fine.

I want to leave it on permanently to see if it is ok without the micro SD card inserted but do not want to sit watching for a random restart error.

Seems all apps restart to where they were after the tablet restarts so I do not know what the beast is doing behind my back.

Is there any app that could show me that a restart has occurred?

 

[B. Diddy]

After one of those restarts, I'd guess that the Recent Apps list would reset and become blank. So when you come back to the tablet, you could tap Recent Apps and see if it's blank or not.

EDIT: Scratch that -- I just tried a restart on my Nexus 6P, and it does in fact remember the Recent Apps.

A restart might also show up as a little break in the battery graph, so see if that might help.