For organizations still on T5.2.x or earlier, note that T5.3.19 is not directly installable; you must first upgrade to T5.3.0 (the feature release), then apply cumulative patches. However, given that T5.2.x reached end-of-life 14 months ago, such a jump is long overdue.
Updating these units can be done either (if supported) or manually via a USB flash drive. Option 1: Online Update Connect your head unit to a stable Wi-Fi network. Navigate to Settings > System Message or About Device . Look for the "Updates" or "MCU Update" button. T5.3.19 Update