Bsa tw35rd - BSA Optics Illuminated 1x30mm Red Dot Sight

I purchased this optic for my Saint rifle while in the military, due to my occupation I haven't been able to use it often until recently. The system was always mounted and stored I n my gun safe unless I went to the range where it was carried mounted on my rife and in a padded case. The other day I went outside to shoot it and after about 20rounds the on/off switch popped off to the point that the dot will not stay on or adjust. This is something I've never encountered before and very disappointed about.