Is it possible to replace an iPhone X chip that has failed?

Firstly, it's important to understand that replacing a chip on an iPhone X is a highly complex task. The iPhone X, like most modern smartphones, is designed with a compact and integrated architecture, making any component replacement, especially a chip, very intricate. This complexity is compounded if the issue is related to the motherboard or a central processing component.

Given your experience level – having replaced batteries on iPhones and a MacBook Pro – but without soldering skills, attempting a chip replacement on an iPhone X might be overly ambitious. Chip replacement typically involves micro-soldering and a deep understanding of the phone's electronics, which are skills and knowledge usually possessed by professional technicians.

Here are a few points to consider:

1. Complexity of Chip Replacement: The task involves precise soldering and handling of delicate components. Without the necessary skills and equipment, there's a significant risk of causing further damage to the phone.
2. Diagnostic Accuracy: The Apple Store's diagnosis of a chip failure could be accurate, but there might also be other underlying issues. Professional repair services can provide a more thorough diagnosis.
3. Availability of Tools and Parts: Professional repair of such nature requires specialized tools and genuine parts, which might not be readily available for individual consumers.
4. Risk of Data Loss: DIY repairs on complex components like chips can lead to data loss. Professional technicians often have the means to minimize this risk.
5. Warranty and Support: If your iPhone is still under warranty or eligible for Apple support, any unauthorized repair attempts could void these benefits.

Considering these factors, it's advisable to seek professional repair services. There are reputable technicians and repair shops that specialize in smartphone repairs, including complex issues like chip failures. They would have the necessary tools, parts, and expertise to handle such a repair.

While it's commendable to undertake DIY repairs for simpler tasks, chip replacement on an iPhone X generally falls outside the scope of home repair, especially without soldering expertise. It's safer and more effective to rely on professional services for such a complex issue.