Sennheiser MTW 3 Cannot Power On After Months of Not Charging

I have a MTW3 that was left untouched for months and the battery went flat. Decided to take it out and charge. After hours and hours of charging, the charging case led light somehow cannot turn green. So I decided to check and take out the earbuds and immediately the led light turns green. Putting the earbuds back in will make the led green go amber endlessly. I tried to power on the earbuds by pressing and holding but I still cannot turn it on. I even tried to clean the connectors and it still cannot get the earbuds to power on.

I tried to google for hard reset and it says hold the earbuds for 6 seconds, but it did not work. Any other steps I can try?