Ericsson F3507g Mobile Broadband Minicard does not power on

[lbreuss]

Symptom:
The F3507g does not power on. Access Connection can't power it on.

The F3507g used to work flawlessly 2 weeks ago. Excellent WWAN connection via Access Connection. Maybe the recent Windows Update broke it?
The Lenovo Hotline does not seem to know of this problem. They just told me to reinstall the usual software components.

Actions so far:
- did a Lenovo System Update of most bloatware components
- reinstalled the Ericsson Wireless Core Module
- reinstalled the Access Connections software
- disabled and even uninstalled the f3507g device. Vista recognizes it as new hardware, I installed the Core Module manually, but still to no avail.

All devices seem properly installed, no question marks in the device manager.
The Ericsson Wireless Core Module installs the following devices:
- USB controller, Ericsson F3507g Mobile Broadband Minicard (MBM) Composite Device
- Smart card readers, Ericsson F3507g MBM PC SC Port
- Ports, Ericsson 3507g MBM Device Management (COM7)
- Ports, Ericsson 3507g MBM Device GPS Port (COM8)
- Network adapters, Ericsson 3507g MBM Network Adapter

Any ideas what to try? System Restore regularly thrashed my disk, but now shows there are no System Restore Points available.