MY BATTERY WENT LOW,I RECHARGED THE PHONE AND THE PHONE REFUSED TO START UP EVER SINCE THEN,I TRIED HARD RESET ON THE PHONE BUT IT COULDNT WORK.IF I PRESS THE POWER BUTTON WITH THE VOL DOWN BUTTOM IT WILL BRING OUT THREE COLOURS,WITH A SECURITY UNLOCKED. THE COLOURS ARE RED,GREEN, BLUE AND WHITE.IN THE RED COLUM IS WRITTEN DIAM100 MFG 64M SPL-1.40.01 iNex MicroP-Diam (LED) V11 on the green colour PSOC-Diam STAGE_PVT v0x32 BLUE IS EMPTY AND ON THE WHITE LIGHT IS WRITTEN SERIAL.

Try another battery - yours might have died and it will not charge any more.

Mine did the same thing I think the protection on the phone to shut it off when it reaches low lvl did not work I had to put my battery in my hero to get it recharged so there must be a flaw with the phone charging a completely dead battery maybe it has to have enough juice to know it has a battery in it ......

try a new battery

this is problem with your hardware.......

Have you tried disconnecting the battery & then re-connecting it??
I had a problem with my cordless phone-it kept saying 'low battery' on the screen, & when I called customer support they said I needed to reset it. I couldnt figure out how! I took the battery cover off, & disconnected my battery, then re-connected it & the message on my screen was gone & it worked fine!

Check the battery connection, if the battery is loose/moves around when you touch it with your finger, try putting a piece of paper on top, or the side, or which ever way it moves. So the battery will still touch the battery contacts. If this isn't the case, try doing a hard reset. Go to start>settings>system>clear storage. (It's like this in my htc diamond, not sure about the touch HD, but should be same) which will erase all data/contacts. Make sure you sync your contacts to your pc to save them!

I just had this happen to me yesterday. I fought with my phone for about 3 hours removing the battery and trying to restart it. It would take about 5 minutes for it to finally boot and once it did the touch screen would not work. So I did a hard boot and within 5 minutes my phone was back to normal. I lost all my contacts but I just did a restore with the backup software. To do a hard boot hold down the red and green buttons on the front of the phone and push the reset button on the bottom of the phone with the stylus. The reset button is on the right side of the power/usb plug. As I said my phone was back to normal in just a few minutes.

a new battery tried yet, battery tests , with a volt meter
only show if cells are shorted, or low charge state (SOC)
only load tests on battery show weak cells.
the top failure on something like this is the battery.
unless dropped.(and any fail possible)
HP has a real forum. why not ask there.
but battery, is top suspect


https://h30434.www3.hp.com/

It's only a guess, but sounds like you will need a new battery. The blinking LED is common with a bad battery.
Ron-

I would take out the battery and keep the power button pressed for 15 seconds. After this power cycle, put the battery back in and try to turn it on.