Frustrating, because the restore is usually the fix — so when the restore itself fails, it feels like a dead end. It usually is not. Work down this list; it is ordered by how often each one is the answer.
Browser. CircuitBlocks needs a desktop Chromium browser — Chrome, Edge or Opera, up to date. Safari and Firefox cannot connect to the hardware at all, and neither can phones or tablets.
The permission pop-up. When you press connect, the browser shows a small window asking which device to use. Your device must be selected there and confirmed — if the window was dismissed, nothing connects. Reload the page and try again, watching for it.
The cable. Many USB cables are charge-only with no data wiring. Use the cable from your CircuitMess box, or test the cable by connecting a phone to the computer — if no file-transfer option appears, that cable cannot carry data.
The port. Plug directly into the computer, not through a hub, a monitor or an extension. Try a different port.
Other software. Close anything else that talks to devices over serial — another CircuitBlocks tab, Arduino IDE with a serial monitor open, or similar tools. Only one program can hold the connection at a time.
Power and restart. Make sure the device has power — charge it, or fit fresh batteries if yours takes them — then restart the browser and try once more. If another computer is available, trying it there tells us a lot.
If the restore starts but stops with an error part-way, do not worry about the device — an interrupted restore does not brick it. Unplug, plug back in and run the restore again.
Still failing? Email [email protected] with your order number, which device it is, your operating system and browser, the exact error text or a screenshot, and whether the computer itself shows the device when plugged in. That last detail matters: a device the computer can see but the browser cannot points somewhere different from one that is invisible everywhere.
If the computer shows nothing at all when you plug in, start with My computer doesn't recognise the device when I plug it in. What's wrong?.