Interactive exchange on troubleshooting a malfunctioning pool probe

Client:
Hello

Technical Advisor:
Hello. How can I assist you?

Client:
When calibrating my probe, it works with PH7 but PH4 shows an error.

Technical Advisor:
It's probably a faulty probe. Please do this test: https://ph-redox-pool.com/gb/content/16-ma-sonde-ph-est-elle-hors-service-

Client:
The probe is from 2018.

Technical Advisor:
That's fine for a pH probe.

Client:
It has always worked, I bought it with the pool.

Technical Advisor:
It happens! Do the test, you'll know.

Client:
I did the test with vinegar, it doesn't change.

Technical Advisor:
It's dead, a pH probe is just a type of battery... Do you have the pH perfect? Send me a photo of your current probe, no need to disassemble it, I will check. There are two versions.

Client:

Technical Advisor:
This one: https://ph-redox-pool.com/gb/zodiac/71-pH-Probe-for-pH-Perfect.html. But you need to keep the black part and the O-ring.

Client:
Has the probe been shipped?

Technical Advisor:
Yes, it has been shipped.