Hey tryol,
thank for providing and maintaining all this information! Do you know how I can downgrade my Kindle to 5.13.3 or jailbreak my Kindle with firmware 5.13.7?
I happen to have a Kindle PW3 (G090G1) with firmware version 5.13.7 (3763000075). I tried the firmware updating (or downgrading?) tutorial to get back to firmware 5.13.3 since 5.13.7 is not supported, yet. However, after I put the downloaded update.bin file on the Kindle and disconected the USB cable the device told me
"Update Error An invalid update file has been loaded on your device. Please go to
www.amazon.com/devicesupport to access the Kindel Software Update page or to contact Kinde Customers Service for assistance."
After closing this dialog the file was delete from my kindle.