Samsung Galaxy J5 (2016) power button

Hello,

No, glue is a very bad idea...

Glue will make things worse.

 but if I shake it a bit (or hard enough) the button comes off again.

In that case, it’s not put back on properly...

Unless it’s broken...

It would be better to have it put back correctly by a repairer or someone else...

“Is progress nice? Tomorrow, when we give a book to a kid, he'll turn it every which way to see where the batteries go.”
Coluche

For everyone who has the same problem as I do and the power button no longer works (like mine does now), there are solutions to turn it back on:

I - Phone with a "detachable" case

You need to remove the case, charge the phone and then unplug it. Right after that, you should remove and reinsert the battery and it should normally turn on. I don’t use this method due to potential risk of damaging the phone.

II - Phone with a "glued" case (also works for phone with a detachable case)

1 - With the "physical" Home button

You need to press the Home and Volume "-" buttons simultaneously and then plug it in. A turquoise blue page (or a similar color) will appear and ask you to install a custom OS. You should press Volume "-" to restart it. This is the method I use.

2 - With the "digital" Home button

You need to press both Volume buttons simultaneously and then plug in the phone to reach the same page. After that, you’ll need to press Volume "-" to restart it.