Because Wisdom Share is used by many different brands, there isn't one single "official" website. However, you can find updated firmware through these reliable channels:
If the TV won't turn on, you may need to open the back panel and look for a code printed on the green circuit board (e.g., TP.MT5510S.PB802 or T.MS638.739 ). Where to Download Wisdom Share Smart Cloud TV Firmware
Updating your TV software isn't just about getting new features. It's about:
Sites like XDA Developers or Firmware-File often host archives for various board numbers.