Edit: Oh... I just found your Dead screen thread, in which you already thought of a (non Planet?) HDMI adapter. Sorry about the noise below then...
One somewhat costly and possibly slow to arrive approach, might be to get a Planet HDMI adapter. In spite of "Gemini" in the name, the same adapter works with the Cosmo and Astro as well.
https://store.planetcom.co.uk/collections/planet-accessories/products/gemini-hdmi-video-cableOn the Astro, it is a bit painful to use. On the other Planet devices, you could plug it in whenever (provided a certain setting was on). On the Astro, the only opportunity to activate external HDMI is during boot, which on the other hand, has the "advantage" of not requiring any settings beforehand.
When my
V07 update went wrong and the screen in my Astro stopped working, I plugged in the adapter in the left side USB-C port, connected an HDMI cable to the living room TV and forced a reboot by holding the power button for close to ten seconds, until the Astro vibrated shortly. That gave me an external screen to work with. (I also tried a 24" Dell monitor, but it didn't like the HDMI signal).
While the previous Planet devices would output the same resolution as their internal screens, the Astro outputs a 720p picture at 60Hz, which isn't ideal but mostly workable, especially after tweaking the screen scaling and the fonts to the smallest possible.
As, in my case, touch doesn't work either, I used keyboard shortcuts to get into the settings, turned on bluetooth and paired a bluetooth mouse. While in flight mode (might not be necessary, but I don't know how the Astro would otherwise have reacted to me opening the SIM tray) I inserted a micro-SD card for file backup (which I preferred over online backups).
That left the right side USB port free to plug in power. That side does not support fast-charging but can keep the device powered. After adding a wired headset, I had myself a kind of "stationary mobile", allowing me to use whatever backup tools I want.
