Download Android Pie 9 stock firmware for Transpeed T98 6K TV Box from here or here. Download previous firmware from here. Flash it from PC using LiveSuit v1.11 or from SD card using PhoenixCard v3.09.
Archive name: Transpeed_6K_H6_4_648M_20191118_1809
Archive file size: 838 MB
Model: Transpeed T98 6K TV Box
Platform: Allwinner H6
Firmware upgrade steps
Step 1: open My Computer – Management – Device Manager – Universal Serial Bus Controller-USB Device-Browse Import Drivers (PhoenixSuitV1.10).
Step 2: Find out and decompress the Phoenix Suit V1.10.rar, install Phoenix Suit.
Step 3: Open the Phoenix Suit and click the anchor icon and switch to firmware panel, then click import the firmware.
Step 4: Prepare a cable with 2 USB connectors. First of all，USB connector to connect your computer. Use toothpick or needle to stick in the AV interface, Press the Reset button, Don’t let go. Then, please hold on pressing it Use 1 USB connector to connect the USB2 (attention!) on the Android TV box.
Step 5: Please click YES(是），then the Phoenix Suit will work, and you can release the reset button. When it shows 100%: Burning successfully, it means the Burning Procedure finished successfully.
Caution Please do not update firmware unless you know what you are doing, you really want it or it is absolutely necessary. Firmware updates may occasionally have bad results, like bricking your device, temporarily or permanently. The firmware update process is done entirely at your own risk. Before attempting to update the firmware, back up your data.