Tp.sk518d.pb802 Software Free Download [better]

Before downloading any files, you must match your TV's hardware specifications with the firmware to avoid bricking your motherboard. 3-in-1 Smart Android Core Board

Plug the TV back into the AC power while continuing to hold the button.

You can typically find the official firmware from the TV brand's support page. However, many generic boards like this use community-sourced firmware. Here are some reliable places to search:

Disconnect the television completely from the AC power mains wall outlet.