Sony VAIO PCG-7141L No Video

I'm tryng to fix my cousin's laptop ...

Sony PCG-7141L, VPCEF25FX running W7 Home Premium 64 bit.
A child knocked it off a table a long time ago. From that point on there's been no video on the laptop's screen.

Attaching an external monitor allowed full use of the laptop for years.
Just recently, there's no longer video signal to the external monitor.
The LCD lights-up but looks like cracked glass or crumpled black and white paper with blue vertical lines on the white part. Note that there are no cracks or breaks in the actual glass.

I've tried Fn+7 to toggle between LCD and external monitor.
I've cleaned the RAM and RAM slots.
I've removed the HDD and scanned it externally with MSEssentials on my laptop. It found 5 thrreats. Three were serious. MSE claimed one sent info out to attackers and another allowed attackers to run software on her computer.
I've tried to boot from a W7 64-bit disc while pressing the Fn7 to toggle between screens.
I don't know the key sequence to get into the BIOS.
I can't change the BIOS if I can't see it on any screen anyway.
I don't have a tech manual.
I'm downloading a Linux LIVE disc but, again, what good will that do if I can't see anything on any screen. Would a Linux Live disc send video signal to both the LCD and external RGB automatically?

The specs of the computer are listd two posts below this one.
It seems that it uses a PCIe video card.
Sony told support email told me he couldn't find the card for this laptop.
He advised me to call someone to ask which card. It's an ATI but Sony could have modified it. He said they don't recommend endusers to open the laptop. He advised me to take it to a Sony service center. I wonder if I could install it and what the cost would be or what the cost of having them do it would be. My cousin can't spend a lot on this. Never mind that we don't know if swapping the video card would solve the problem. Would Sony check it out for a nominal fee or for free and tell us what the problem is so she could decide if it's affordable for her to fix?

I suppose the video RAM could be bad.

Any help and links to technician's manuals would be greatly appreciated.

 

Update > It seems the model listed on the back, VPC-7141L isn't the model number. The Model listed on the lower right of the LCD is VPCEF25FX.

Thank you for any help, direction to go, advice.

 

MPN: VPCEF25FXBI

Key Features
Weight: 6.7 lb.
Laptop Type: Mid-Size Laptop
Use: Home Use

Processor: Athlon II Dual-Core 2.1 GHz
Installed Memory: 4 GB (DDR3 SDRAM)
Hard Drive: 500 GB Serial ATA, 5400 RPM
Display: 17.3 in. LED
Operating System: Microsoft Windows 7 Home Premium 64-bit

Processor
Processor Manufacturer: AMD
Processor Type: Athlon II Dual-Core
Processor Speed: 2.1 GHz

Memory
Installed RAM: 4 GB
RAM Technology: DDR3 SDRAM
Max Supported RAM: 8 GB
Installed Cache Memory: 1024 KB

Hard Drive
Hard Drive Capacity: 500 GB
Hard Drive Rotation Speed : 5,400 RPM
Storage Controller Type: Serial ATA

CD / DVD
CD / DVD Type: Blu-Ray
Optical Drive Read Speed: 4x (BD)

Display
Display Tech: LED
Screen Size: 17.3 in.
Display Max. Resolution: 1600 x 900

Video
Graphic Processor: ATI MOBILITY RADEON HD 5145
Installed Video Memory: 512 MB

Audio
Audio Output Type: Headphones · Sound card · Speaker(s)

Operating System
Microsoft Windows 7 Home Premium 64-bit

Platform: PC

Technical Features
Expansion Ports: 4 x USB 2.0, VGA out, RJ-45 (NIC), HDMI
Input Method: Keyboard · Numeric Keypad · Touchpad

Networking
Networking Type:
Bluetooth · Integrated 10/100/1000 Network Card · Integrated Wireless LAN
Data Link Protocol:
Bluetooth · Ethernet · Fast Ethernet · Gigabit Ethernet · Hi-Speed USB · IEEE 802.11b · IEEE 802.11g · IEEE 802.11n

Battery
Battery Run Time: 1.5 Hours
Battery Technology: Lithium ion

Dimensions
Width: 16.1 in.
Depth: 10.79 in.
Height: 1.5 in.
Weight: 6.7 lb.

Miscellaneous
UPC: 27242804166
Product ID: 101254859
Family Line: Sony VAIO

 

Sounds like a failure of the hardware. If you still have Windows 7, windows key + p will change monitors "projector". The screen might not be cracked, but the LCD inside can be damaged