Aukey EP T25 do not appear in bluetooth devices

Hello,

I have a little problem.

When I take my Aukey EP T25 earphones out of their charging case, they do not appear in the bluetooth devices on my smartphone. I have tried with several different smartphones and I cannot connect, they are invisible and do not appear. I loaded the box entirely.

The first day it worked, I put them back in the box but now they don’t work anymore.

What to do ?

thank you so much

Now there is just one earphone that has connected but not the second.

Yet is it the main earpiece that must transmit the sound to the other earpiece?