Megadesk & Companion not working. Error: "Reading from UART timed out at byte 0!"

[cdelog]

I love the Megadesk idea, and realllllly want mine to work! :)

I purchased the megadesk and companion. Flashed the megadesk per the instructions. It seems to work and (when on USB power) I integrated it into Home Assistant with no problem.

I powered on the desk, and the companion is beeping repeatedly with 3 tones of increasing frequency, on loop. Each trio is accompanied by an error message in the ESPHome browser shown in the attached image. The repeating message is:

[E] [uart:015] Reading from UART timed out at byte 0!
[W] [component 237] Component took a long time for an operation (103ms).
[W] [component 238] Components should block for at most 30ms.

Do you know what could cause this issue and how to fix it?

NOTES:

• I have no buttons, so no ribbon cable is connected to the companion (the used desk did not come with buttons, and I was hoping to use Megadesk through HA with no buttons). If the buttons are UART then this might be the issue??
• I had to make the connector cable. The Megadesk Companion is powering up, which seems to suggest I wired it right. I wired pins 1,2,3 -> 1,2,3 (i.e., direct pinout, NOT reverse pinout)

[gcormier]

So if I understand you made your own 5-pin connector between megadesk and companion?

[cdelog]

Hey! No. I'm using the included 5-pin cable between the megadesk and companion, and the included 3-pin cable between the megadesk and the desk leg. The only cable I made was the connecting cable between the two table legs, and then I'm missing the button ribbon cable.

Everything else are factory cables.