Not sure I'm in the same boat...
is anyone seeing the same as I am - I also can't boot into Recovery since nightly 20130824. I can boot into Download mode... and... I can still boot into my current CM10.2 nightly (20130824)!!!
I've tried reflashing CWM using ROM Manager, even a few times... but nothing changes. Trying to get into recovery using VolUp+Home+Pwr doesn't work (after Samsung GT-N7000 white text... blackscreen (which I can see is still 'on'). If I try to boot into recovery using Rom Toolbox or similar, it behaves the same and I can only get it to reboot into the ROM once I've pulled the battery out and then put it back in and connected to a charger so the battery charging icon shows... which somehow clears the 'boot into recovery' flag somewhere.
Very concerned... saw something in the changelogs back at 20130824 about recovery fixes and wondered if this might happen. The first time I got it to boot back into the ROM something wasn't quite right with the internal/external SD mounts... all my ringtones and alerts etc. were reset to just numbers (e.g. 40125) which actually happens more often than I expect... but this time I couldn't find the ones I usually use in the selection list.
I rebooted with SD card out... then re-inserted it... and then things went back to how they should be and I could see and select my preferred tones again.
Have tried booting into Recovery via app, via hw keys... with SD card in, SD out... SIM card in... SIM out... both SD and SIM out... there's just no way into recovery.
Using ROM Manager I also tried to setup the alternative Recovery (TWRP) but that also gets stuck with the message 'ROM Manager has been set up to use your existing recovery installation'. but same behaviour when trying to boto into recovery.
I've also used Android Root Toolkit to try save/protect Root... Restore Root.. etc. but to no avail.
Any ideas... please?
EDIT: Thanks for the Odin3 / PhilZ Kernel advice - that seemed to work.
Question: Now that I've got back to recovery and updated to nightly of 20130826, did I overwrite PhilZ kernel?