Thinkpad Yoga S1 not charging and stuck at 800mhz - even after servicing

Question

After giving up and sending my Thinkpad in for service, it still (after being at the depot for two weeks!) still not fixed.
I have to admit, I am dissapointed with Lenovo's service so far, it is clear the technicians did little to no diagnostics at all to confirm the issue was fixed.
My issue is as follows:
1) The computer will run INDEFINITELY on the power adapter.  This is NOT a case of a faulty power adapter (occurs with two different adaptors) or a faulty power port (again, the machine will run until the cows come home on the adapter.
2) The computer is stuck at 800mhz.  I can get it 'unstuck' as long as it is unplugged and I toggle the multicore option in BIOS.
3) Once plugged in, the CPU will return and remain at 800mhz, even if it is unplugged, shutdown, rebooted, etc.
4) The battery will not charge.  The laptop will run off battery power if the battery has power (came back from the depot at 99%, down to 90% now) but will not charge the battery at all, only maintain the level.  This is the case whether the computer is in Windows, or turned off.
This is Windows 8.1 by the way, so there is no option to set a charge level to maintain.  That being said, last time (before I sent it in) I drained it to < 50% and it still never charged, even when it hit 0% and the laptop stopped detecting the battery (but still ran off the ac adaptor).
The unit also had some ghosting on the LCD, and it took me a while to convince the techs to swap it out.  I think my mistake was I wiped the unit, and so they were too lazy (?!) to actually test it, since once you use the computer for 5 minutes it was very obvious (I offered to send pictures, as I documented the issue but they declined).  That issue has thankfully been resolved. 
This is the first "post-IBM" Thinkpad I've owned, and I have to say between this and that abysmal clickpad I am not impressed.

Answer 1

I recently had this problem too with my Yoga S1 after a system driver update.  I noticed during the updates that I received a message that the BIOS update failed.  The message came and went very rapidly and the updates continued and completed with no problems.  Usually when a firmware update fails, nothing in the BIOS is really changed.  I turned the computer off and thought nothing of it.  The next time that I turned it on though I too had this problem.  After repeated pressings of the power switch and pressing the reset button it finally booted and seemed like all was good, until I did a reboot, and it started again.  After much more pressing buttons it finally did  boot again.  That's when I remembered the failed BIOS update.  I didn't trust the auto update program, so I went to Lenovo's site and dowloaded the latest firmware and attempted to update it manually.  When I ran the update program it failed again.  What I wound up doing was just keep trying.  After repeating the update program four or five times, it finally completed successfully.  I have no idea why it kept failing or why after many attempts it finally worked.  After the update finally worked the problem seems to have been resolved, at least it hasn't done it again,,,yet.  Hopefully this will give some others hope in that it can be resolved without sending it off if you can get it to get it to boot again.