Sony MHC-V90DW Help Manual page 51

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 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 and
network while updating.
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