What does the string received from the output of the sensor mean?

Question

Sensors

When the CO2 sensor MH-Z19B is turned on, I receive a string from it on the UART

b"Downloading Image To the STM32F051k8 Internal Flash......\r\n
Waiting for the file to be sent ... (press 'a' to abort)\r\n
CCCCCCCCCCC\r\n\n
Download timeout!\r\n
Execute user Program!\r\n\n"

This is fine? What does this mean?

After that, the sensor does not respond to commands, and until it is restarted by power, it is not possible to get something from its output. Perhaps I am doing something wrong.

I rummaged through the infernet, but found only in one place the same line, where a friend asks a question similar to mine. Didn't find an answer there.

Answer 1

Something went wrong and the sensor wants to get a new program.
Something like that? https://github.com/Disasm/mh-z19b-firmware