Hi,
The 601 error code actually refers to your notebooks main battery ( not the rtc cell on the system board ) and usually occurs when the storage capacity has fallen below 25% of its original value.
The only solution is to replace the battery.
This is a warranty item, so if your notebook is still under warranty, contact HP and arrange for a replacement to be sent - you can check your warranty status Here.
If you live in the US, contact HP Here.
If you are in another part of the world, start Here.
Regards,
DP-K