This usually means the that the chipset or the cables are loose.

Push the chipset in the back until it clicks and it is firmly attached to the screen.
Also make sure that black and red cables are plugged in.

When the USB is plugged in, the LED light in the chipset should show as green/yellow.

Use this Video Tutorial know how to remove and plug back the chip: https://www.youtube.com/watch?v=aRB8zr_93wU

Most errors are related to a weak Wifi connection.

The device does not have a strong wifi receiver so please make sure 

it is connected close to the wifi source.

The Second most common error is a wrong API key, make sure the API was entered correctly and that your account hasn’t been suspended.

Sometimes the API could be down for a few seconds, this is normal for these external websites.

Unplugging and plugging back the USB cable to restart the display will usually fix these errors.

Not having enough power source may cause this, make sure

you are giving enough power (preferably using a wall outlet).

Recommended wall adapter is 5V and 2.1 Amp  (cheap 1 Amp will not work).

If you see MATRIXBOOT as the name of the drive, this means the device is on RESET mode and it happens when the RESET button gets pressed twice. Just press the RESET button 1 time to get it back to normal and you will see the name CIRCUITPY when connected.

Yes, it is easy to add/edit/remove stocks or cryptos, just edit

the secrets.py file where you entered your WIFI credentials.

You can add about 10 or 12 stocks/crypto symbols.