the real chance of bricking during a9lh installation is downgrading or the ctr transfer step. I haven't looked at the guide for a while, but there were brick risks with sysupdater. I'm not sure if it still uses that, but make sure the firmware being installed is correct especially knowing if it's new or old. I think the last time I looked at the guide, it had divided systems to reduce brick risks. the guide is fully covered though, so the apps and the text used should prevent bricks. usually, a brick is the result of user error now, so follow the guide to the letter.