Before you start replacing hardware, maybe you'll get lucky: check the PID constants. If they are completely out of whack (actually way too large) , you could be getting rapid temperature cycling that would have these symptoms.

Thanks for the suggestion. I did check all PID params and they all match the stock values. I also snugged the internal OPV by a 1/2 turn (per Clive's suggestion) and that has not resolved the issue either.

With "TR=1" I can see the temperature on the panel jumping around from one second to the next. It will be at 112c, then at 103 a second later. No wonder the temp doesn't match the set value - there's clearly something wrong with either the temp sensor or the computer. It's gonna have to go back to be replaced/fixed.

Thanks everyone for the help. Long time lurker, first time poster. Will be back once I have a working machine.

I'd try to check the connection of the temp sensor to the PID .. if you haven't sent it back yet.. maybe a badly crimped wire.. or broken wire.

Can't see any issues with wiring, everything looked tight to me. But, I'm not an electrician and really don't belong inside an espresso machine in the first place!

I'll be waiting for a response from Clive and update this thread when I know more about what went wrong, for posterity. Thanks everyone for the thinking/replies so far.

I have a question regarding the flash boiling method. I've read some threads about it, among them of course Jim's explanations and I also watched his videos. But I think I have not read anything on this: How do we know that the offset doesn't change between 90°C and 100°C? What I mean is, the e61 group cools down because of the exposure to the air which is at room temperature, say 22°C.
Now the hotter the boiler and group temperatures are, the greater the difference between them and room temperature is and thus the faster they cool down.
At 103°C boiler temp the offset may be 10°C in a specific environment and the water will have 93°C at the group. The same machine in the same environment might show a larger offset of say 13° at 114°C boiler temp and 101°C group head temp because the hotter water gets cooled down more.
This would mean that even though the water of a machine came out flash boiling at exactly 113°C boiler temperature, the offset at a normal espresso brewing temperature could be lower than 13°C.
Does this make sense?

It makes perfect sense. Let's put numbers to it.

Suppose your room temperature is 22.5C. You want the group at roughly 92.5C. So the heat loss is based on a temperature difference of 70C. When you raise the group to a 100C, your heat loss has risen to a factor of 77.5C, or about 11% more than it was at 92.5C

This means that if the brew boiler needs to be X degrees higher than the group to keep it at 92.5C, it has to 1.11*X degrees higher when the group is at 100C. This suggests that the offset should be lowered by 10% after you have determined it via the flash boil method.

So for my machine, I should drop it from 14 to 13, and if 10C is the ballpark offst for most machines, it should be about a 1C smaller than the flash boil method indicates for all machines. Given the finickyness of measuring gear, and the margin of error for the flash boil method, this would take some time to verify experimentally. But the physics seems airtight; and it looks to be a legit correction factor.

Good catch!

Thanks, Jim! I'm glad I could contribute something useful.

I got my Bianca just yesterday and conducted the flash boil test. But I'm having a hard time to detect the exact point where the flash boiling is setting in. I'd appreciate your opinion:
The hissing really starts at 100° but the bubbling at 102°

You want immediate hissing, boiling and steam, without delays. IMO, from the video, that's at 102. So you want to set your offset up by (now) 1C. All in all, your machine seems very close.