SPI communication issue

[burg]

history:
I soldered a board that can drive two brushless dc-motors (common for modelmaking). After solving some problems both motors were running properly.
After adaption of the mechanical part, one mosfet wasn't working any more. Removing the mosfet made clear that the TMC389 driver stage for this mosfet wasn't working any more.
I ordered a new TMC389 and replaced the old one. After providing power to the mosfets, one path was fully destroyed (not that one with the previous problem). I don't know the reason but it could be a soldering problem.

problem:
I removed the two related mofets but now the communication via SPI is not working any more, but I'm not sure if this problem still occured before the failure with the mosfets.
The signal on SDO is about 1 Vdc overlaid with small part of signal on SDI and SCK (few millivolts). Do you think I destroyed the TMC389?

I don't know how to prove proper operation of the TMC389 in the removed state.
Before ordering a new TMC389, I want to clarify the reasons for the problem (I unfortunatelly got no financial support from the university and the tmc389 is not cheap part for a student)

thank you in advance.

[TRINAMIC_BD]

Hello,
in order to find a defective IC, you can check the supply current - this mostly gives a hint if something is wrong. Also you should check the voltages VHS and 5VOUT against the datasheet value.
When switching on a newly (hand-)soldered device - be careful - optimum is to slowly increase the voltage and monitor supply current and voltages. Then a soldering issue will not destroy anything.
SDO should show full VCC_IO levels once CSN is low and VCC_IO is supplied.

[burg]

Hello,
thank you for fast reply.

It seems like my TMC389 is defective. 5VOUT is only 2V.
Normally I operate a new soldered circuit with current limitation. As I just replaced the TMC389 by a new one I was quite careless.

Do you have an idea why the previous TMC389 driver stage for only one mosfet wasn't working any more? I don't want to make the same mistake again.

[TRINAMIC_BD]

Mostly, a defective MOSFET is likely to destroy the driver stage in the chip. When you as a first test try at a relatively low supply voltage of max. 10V, this is very unlikely to happen.