Bootloop after misconfiguration ControlX

Recently I've flashed linux dual boot on my CX CAS rev K, it works perfect, but after a while I set the wrong partition as default boot partition, the calculator went into a bootloop with a black&white loading screen, it goes to around 50% and restart foever.
OS installed: 3.6.0.550
Boot1: 3.00.99
Boot2: after nboot loaded it reports 255.25x.xx.x (forgot exact number but I think it's dummy)
Tried started with key combos:
doc+enter+ee, noting happen
doc+enter+ - , stopped loading anything and a floppydisk icon (?) pops up
doc+enter+2 , stopped loading anything with a gear icon pops up
esc+menu+ -, nothing happen
I believe it tried to boot into partition without any system
Should I buy a USB-TTL and try to flash boot2 partition?
OS installed: 3.6.0.550
Boot1: 3.00.99
Boot2: after nboot loaded it reports 255.25x.xx.x (forgot exact number but I think it's dummy)
Tried started with key combos:
doc+enter+ee, noting happen
doc+enter+ - , stopped loading anything and a floppydisk icon (?) pops up
doc+enter+2 , stopped loading anything with a gear icon pops up
esc+menu+ -, nothing happen
I believe it tried to boot into partition without any system
Should I buy a USB-TTL and try to flash boot2 partition?