Strange behavior on Nexus 4, Android 5.0.1 (issue with Google Play Services?) Apps don't autostart, Google apps don't work, phone freezes
The uninstall updates and force stop buttons are greyed out because of the device administrator's setting. As you already know, you must uncheck the checkbox for Google Device Manager as device administrator first, afterwards the buttons are active.

I did that a couple of times myself because I have the same problems on my Galaxy S4 with the newest Lollipop. There are two problems, though:


Immediatelly after reboot of the phone, this setting takes a while to kick in. Only after one or two minutes the device accepts to remove that device admin setting. So give it some time and several tries.
From time to time, after reverting to factory version of Google Play services, they get auto-updated to the newest version again, regardless of the auto-update settings you might have.


I figured out that for me each version of Google Play services of 7.0 and newer definitely will crash. Version 6.7.76 is the last one that works for me. You can download and install the APK at apkmirror.com. At least for as long as it takes to auto-update it again...