urgent issue with ebay hid batteries

[R10500]

ok so i previously had a problem with 1 of the 2 8700mAh batteries for my 85W light. it wouldn't cycle through all modes when plugged into the flashlight any more but would still do so when removed. now it doesn't do anything when put in but still switches on when removed. i tested its voltage and got 7V when off and on low mode. the funny thing is when i contact the points 2 more times the red LED blinking thing goes off, which should indicate a voltage below 9V according to the manual. i cannot measure the voltage on the other higher modes.

with my other battery that's been working fine and served at least 40 minutes total, i get 9V on medium and 10 volts only on High. maybe this is why my light isn't much brighter than my 2000 lumen LED.

if anybody has a solution to this please chime in. i don't think the seller accepts exchanges now since its been way longer than a fortnight.
i tried looking for this one thread that had people's measurements of their batteries' voltages but i can't find it now.

 

[VidPro]

Lots of info, but not enough to figure out anything.
i think you need to first explain the light, its power source, what light item is it exactly.

 

[R10500]

i'm afraid i don't know what you mean. but the light is the ebay 85W HID that more humble pockets like mine can only afford lol the battery is aparently made up of 9 18650 unprotected Li-ions, arranged in 3s 3p in a metal tube. the voltage is way too low which wasn't the case when i received it a month ago and when i plugged it back into the charger after finding it very low on voltage, it showed a full charged but voltage remained the same. what should i do now?

 

[Omenwolf]

Do you have the capability to cycle the batteries individually? Sounds like one or 2 of the cells might be bad . If you can cycle them individually you can figure out if an individule cell is bad and replace it.

 

[R10500]

yeah what i thought too. sadly no. looks like i'll be forking out some $$ again for a new one like some other unlucky folks did. some resolved it just plugging the battery into the charger but idk what's up with mine.