Device: an ASUS X00PD, computer: Ubuntu 23.10 with ADB and fastboot installed.
I cannot even bootload the device: On the device I press power + volume up buttons to enter bootloader mode but the device stays there half a second. The device then turns itself down, restarts itself and cycles like that till the battery dies.
I don’t want to go back to stock software, Id install anything that works for this particular device.
Yes. If you can’t access fastboot and the OS, you need to use the Emergence Download Mode (EDL) for you phone (volume down + power).
XDA forums has all the steps and guides to unbrick your device.
Download your firmware file (please check your SoC due to the different phone variants).
Download and compile the QDL tool with some more details about QDL here.
Enter EDL mode.
Flash your firmware as described by the first link in step 2.
Profit???