The fact that you checked it out with an external battery charger does not mean that it is fully charged. It could have water damage. Is the water mark sticker on the battery completely red. I'm assuming you are using an OEM battery which means the model number of the battery is the BTR6200. The water mark sticker should be beside the contacts. If it is completely red and does not have any Xs then it is water damaged.

If you got this battery from China, it is possible that the battery is DOA. A lot of these Chinese aftermarket batteries are pretty crap. Some of these companies buy scrap batteries change the sticker and contacts and sell them as originals.

The best thing to do is actually go to a batteriesplus store and have the battery tested. If the battery is fully functioning then the phone is the issue. Or if you know anyone that has an Eris try using the battery on their phone. If the phone works then your original phone has an issue, if it does not then the battery is the issue.

If these two options are not available then I suggest you purchase another battery to test it out with your phone. Same thing, if the battery you purchase works with the phone then the original is garbage.

Hope that helps.

Did you try battery pull?

I have a three HTC A3288- phones bought from China. They all suddenly stopped powering up, hanging on a message 'htc'. Can someone help to solve this?

I have a fully charged battery in a HTC ERIS and I hold the power button down.
Nothing, I'm getting frustrated with this phone and have used an external battery charger
to confirm the battery is fully charged. Ideas of what to check next?