I did the same thing, except with a status bar battery icon. I went into ROM Toolbox, first installed custom boot logo (worked), but then after I installed custom battery icon, Android kept giving me a "Status bar is unresponsive" kind of pop up, and would continue each time I clicked "force close".
Long story short, I had to use Nexus7 Toolkit to flash the stock image again, as I did not have a Nandroid backup at the time. I do now.
I did email the developer about it, and I was told I needed a deodexed ROM in order to customize. I'm hesitant to install a custom ROM, as I love having pure Android for the first time (I've been using CyanogenMod on my phone and my old HP Touchpad to keep me up to the latest). In time, I may give in, to have more customizations available.