Ignition key in my 2005 Chev Blazer 4x4 will not turn to the off position making it impossible to get the key out, thus the battery drains down.

SOURCE: installing ignition switch for 87 chevy s10 Blazer 2.8L 4X4

you need to replace the electrical part of switch?If os it is down on column under dash will be two bolts holding on with the dimmer switch also

SOURCE: Key stuck in ignition of 2002 chev. trailblazer

Remove the cover of the switch, there is a silver button below the place where you put the key. Press it and the key will be released!

SOURCE: key stuck in ignition. Won't turn to the off position

Sounds like a very warn out lock and tumblers. Try angling the key as you turn the lock.

Harvey N Tawatao

• 3854 Answers
• Posted on Jun 24, 2009

SOURCE: can't remove key from ignition. battery is dead

If the battery is dead, the ignition keys will not release from the ignition. If there is no signal from the transmission shifter that it's in park since the battery is dead, then the ignition lock will not release the keys.  After charging the battery or jumping the blazer to start it and the key's still will not release, try this. 
There is a "plunger" as part if the ignition. Under the steering wheel there is a small removable cap that you can take off and put a small screw driver up into and press the plunger in and it will release the key. Good luck and hope this helps, Keep me posted be glad to help. 

marcial adorno

• 246 Answers
• Posted on Sep 08, 2009

SOURCE: 2005 Chevy Impala ignition switch stuck in off position

if it doesnt turn you have a worn out ignition cylinder, the only fix is to replace it, Code the ignition lock cylinder, if necessary

CAUTION:Perform the body control module (BCM) theft deterrent relearn procedure whenever you replace the ignition switch lock cylinder.