How to install Android completely as new to ASUS Eee pad transformer?
If you can access APX Mode, you can restore a stock ROM using Easy Flasher.

The steps are the following:


Check if your Asus Transformer is supported.
Download Easy Flasher
Download the latest stock ROM from Asus website.
Copy the update zip to asusupdate folder (inside Easy Flasher folder).
Open Easy Flasher and hit Flash Asus stock zip


The application will install the stock ROM back to your Transformer, so from there you can root or install a custom ROM without problems.