Troubleshoot Toshiba Satellite Wireless connection

The laptop is L40-17Q .The wireless card is Realtek 8187B.

Problem: No wireless signals detected.

What I see:
- Wireless card recognized by system, MAC address assigned.
- No wireless signal detected. The wireless router is close as 2m and other laptops Toshiba near by detect strong signal. The other laptops detect also the neighbor’s wireless signals (6-7 routers).
- The LED for wireless is not coming ON no matter if I move the switch for wireless OFF to ON many times. I can feel and hear how the switch is moving from OFF to ON position and the other way and I slide it.
- Although I tried Fn + F8 from keypad. On F8 is wireless icon.
- Messages in Windows XP after a new fresh installation (including all the drivers):
o Wireless network unavailable. After Refresh Wireless networks nothing detected.
o In control panel, device manager, properties of wireless card adapter: “this device is working properly (enabled)”.

Things done:
- Windows XP reinstalled (several times)
- BIOS checked – LAN enabled. Tried also enable/disable couple of times, but no influence for wireless, just for wired network chip.
- Wireless card reseated several times.
- Original and latest driver installed and tried one by one.
- Toshiba assistant and diagnose doctor (for network communication) installed and used.

What I cannot do:
- I cannot test the wireless card in another laptop or another new/good wireless card in the existing laptop.

The laptop has BIOS with SLP, but that should not be an issue, because:
- All the other hardware devices are working fine.
- The wireless card worked properly (couple of years) with the same operational system, installed from the same CD.

The laptop belongs to a friend which told me that few weeks ago started to have problem with LED for the wireless. The LED was OFF all the time, but the switch for wireless was ON and the wireless card was working without problem.

Questions:
- Is it the wireless card or the motherboard/switch defective?
- Is it a hardware problem or software problem?
- Any step-by-step guide/suggestions to identify/declare the wireless card defective?