Checking the keyboard layout is the first step because an incorrect keyboard layout can cause special characters to produce different outputs. This can be quickly checked and corrected if needed.

Based on the information recorded by the technician, the network connection appears to be functioning normally. The user's computer is properly configured with an IPv4 address, subnet mask, and default gateway, which should allow the user to access the internet and online videos.
The high download and upload speeds and low ping time recorded from the test laptop also indicate that the network is working well. However, the user's inability to watch online videos suggests that there might be an issue with the network card (NIC) on the user's computer. The NIC might be faulty or malfunctioning, which is preventing the computer from receiving and processing the video data. The technician should try replacing the NIC to resolve the issue.

A digitizer is a component that converts the touch input on a tablet screen into digital signals that can be processed by the device. A digitizer consists of a thin layer of transparent material that covers the glass screen and has sensors that detect the position and pressure of the touch. If the digitizer is damaged, misaligned, or poorly calibrated, it can cause inaccurate touch input, such as selecting the wrong item or not responding at all12. Therefore, the most likely cause of the issue in this scenario is a faulty digitizer that may need to be replaced. The other components are not directly related to the touch input functionality of the tablet. A gyroscope is a sensor that measures the orientation and rotation of the device3. A battery is a power source that supplies electricity to the device4. A glass is a protective layer that covers the screen and prevents scratches and cracks5.
Reference
1: What is a Digitizer? - Definition from Techopedia
2: How to Fix a Broken Digitizer on a Tablet | Chron.com
3: What is a Gyroscope Sensor in Mobile Phones? - Definition from Techopedia
4: What is a Battery? - Definition from Techopedia
5: What is Glass? - Definition from Techopedia

Explanation
A cellular card is a device that allows a laptop to connect to the internet using a cellular network, such as 4G or 5G. A cellular card can provide internet access when the user travels and does not have access to a Wi-Fi network. A cellular card may require a subscription plan from a cellular service provider. A Wi-Fi extender is a device that boosts the signal of an existing Wi-Fi network, but it does not provide internet access by itself.
Bluetooth is a wireless technology that allows devices to communicate over short distances, but it does not provide internet access either. GPS is a satellite-based system that provides location and navigation information, but it does not provide internet access as well. References:
https://www.comptia.org/blog/what-is-a-cellular-card