I flashed N900 with PR1.3, upgraded to 1.3.1.

Then I did the exactly the following
0) connected to WiFi
1) added extras-testing repository to the app manager
2) installed rootsh via app manager
3) opened the terminal and ran
sudo gainroot;
apt-get install wget;
apt-get install kernel-power;
dpkg -i dpkg -i omap3-dsp-baseimage-ti_0.i3.6-15+0m6_armel.deb omap3-dsp-libraries-ti_0.i3.6-15+0m6_armel.deb omap3-dsp-hd-codecs_0.3.8-7+0m6_armel.deb

Using the files attached to the very first post.
cp libgstdsp.so /usr/lib/gstreamer-0.10/libgstdsp.so
apt-get remove gstreamer0.10-openmax

Rebooted. The device does not boot, exactly as before.

I observed that when I ran apt-get remove gstreamer0.10-openmax the package mp-fremantle-generic-pr was removed as well.