Probably the battery is on its last legs.
If you can replace the battery yourself , than its not a very expensive experiment.
This one should fit fine - 60mm height, 50mm width, 4mm thickness.
https://www.ebay.com/itm/3-7V-1400mA...sAAOSwZ1lWcQpk
I never opened a glo, so i got the dimensions from a post here.Best would be to measure your battery to be 100% sure that it will fit.
If you cant do it yourself and would need to involve a repair shop, than it probably wont be worth the cash you would need to spend to fix it, depending on your country of residence and electronic repair prices.
If nothing of the above is applicable and money is tight, last and most ghetto solution

would be to get a small powerbank for around 15$ and have it by your side when youre on the road reading so you dont get cut of in the middle, or if youre away from a socket.