# ADB or Wi-Fi no longer communicating!?!

Source: https://forum.modalai.com/topic/488/adb-or-wi-fi-no-longer-communicating
Category: FAQs (https://forum.modalai.com/category/4/faqs)
Posted: 2021-10-08 15:51:23 UTC by Chad Sweet (ModalAI staff)
Replies: 0 · Views: 2109 · locked, pinned

## Chad Sweet (ModalAI staff) · 2021-10-08 15:51:23 UTC

Each PCB is thoroughly tested prior to shipment. If your PCB is no longer responding to ADB or Wi-Fi, it is likely the system flash is corrupted, or "bricked". Please follow the instructions [here](https://docs.modalai.com/unbrick-voxl/) to fix.

[Video Demonstration!](https://youtu.be/6_WzFYnpu40)

With flash, like what is used on VOXL, removing power while the kernel is writing will result in corruption and bricking of the board. It can happen during development when a lot of changes are being made on the board and then power is removed.

To prevent system partition flash corruption:
* run poweroff before removing power: ```$ poweroff -f```
* Use the /data partition for file storage

Linux has a setting for how often the flash is committed to reduce the risk, but of course there could be different side effects. You can see a writeup on the topic [here](https://superuser.com/questions/1057007/adjust-linux-disk-flush-intervals-to-avoid-blocking-user-processes), as it is common in all of this type of single board computers

Your smartphone fixes this by making you press the poweroff button before shutting off power and does not have a removable battery.