Just updated my N3DS and O3DS XL, both using A9Lh SysNAND with no emuNANDS, all old firm files delete etc.
N3DS - fine, using flags 'Use SysNAND FIRM as default' and 'Force A9LH detection'
O3DS - Won't work independently with either of those flags even if used alone, boots into the system without a theme before erroring out to 'Please turn off the Power' etc. BUT works fine if Autoboot SysNAND is also ticked. I redownloaded the archive and replaced the files but had the same behaviour. Bug? Not a huge issue because it works either way.