Write down your screen resolution (1024x600, 1280x720, 2000x1200). Also note the CAN Bus decoder listed (Raise, Simple, Hiworld, etc.). You may need to reconfigure these after the update.
If your device has a brand name (e.g., Teclast, Chuwi, Joying), go to their official website. This is the safest route.
If your device is stuck in a bootloop (won't turn on) or the SD card method fails, you may need PC tools.