problem with battery charge percentage and maximum capacity reading

i have an iphone 7+, although i'm sure it's not unique to this model, that has been in a drawer for between 8 months and a year. when i last looked at it the battery health was around 82%. when i pulled it out, i had to charge it up, naturally, but when i turned on after about 2 hours on the charger, the battery meter only read 2%. when i went to Settings / Battery / Battery Health, it shows my the apple spinny indicator and never shows me a Maximum Capacity reading.

i left it charging overnight and in the morning it was still showing 2%. i've tried it on both 1A and 2.1A chargers, it won't go above 2%.

even if the battery has just crapped out, wouldn't you think that it would still give some sort of Max Cap figure?

can a battery just go bad if it sits around idle for a long period of time?