you have to connect the reader in recovery (rupor-rescue) mode to a linux machine. i used debian...
in recovery mode you have access to the whole internal memory like to an external disk.
you can extract the official firmware and copy the 'PRS-T1 Updater.package' to the reader-partition of the internal flashdisk. the update can be started by pressing home and menu while powering on. (wait till the bar is in the middle and release the keys)
the problem is, that the update only installs, if the version on the reader is lower than the version of the update. there is a check built in the updatepack.
i used a hexeditor in linux, connected it to the reader-memory (sdb) and changed by search and replace manually all version strings found on the disk to 1.0.00.09010. the strings are easy to find, because they are in ASCII and readable in hexedit.
{there is a script on the diag-partition of the reader-memory (version_check.sh). you can start this script via console and see all version-strings you have to search and replace on the disk.}
after replacing all found strings i copied 'PRS-T1 Updater.package' 1.0.05.11130 to the reader-partition of the internal flashdisk once again. i rebooted the device without the sd-card and the updatepack 1.0.05.11130 in the READER partition did its job.
after this update my wifi and usb where back. now it was able to install the official 1.0.07.05070 via usb from windows pc...
do it on your own risk. it is potentially unsave to hexedit a partition's content. but if the device is already bricked, it is just a try.