Sony MHC-V90DW Help Manual page 47

Note
When you update using a USB flash drive, the update cannot be stopped. If the USB flash drive is removed or the home audio
system is unplugged from the power supply during the update, the home audio system will malfunction.
Updating normally takes 3 to 10 minutes.
Do not operate the home audio system during an update. Also, keep the home audio system connected to the power supply
while updating.
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