Issues with Nortel dr5.1 phones

[Suisse]

We have a customer who is having issues with their nortel Dr5.1. When they perform an inbound / outbound call on any phone, then put call onhold, then select a different line the phone would reset/reboot. we tried to reboot the system, swapped lines to isolate issue but issue unresolved. we attached photos and a video to help.

We believe the system has failed but it is possible that we can factory default to resolve.

See photos and video below.

https://drive.google.com/file/d/1GmHA8Uv4bgV_IEDkrfJC5M4z_HYZBn9r/view?usp=sharing

https://drive.google.com/file/d/10wUvro9Zn6m7xzjUUJv5DRS7nVW5ikba/view?usp=sharing

https://drive.google.com/file/d/1L4ObnuyefDcE7fnrRt5v5Tahcp97a69A/view?usp=sharing

https://drive.google.com/file/d/1v2bxW66EcYUdwRanByP6HQNVhJCjt9dH/view?usp=sharing

https://drive.google.com/file/d/1GMZpd75fDH3DG1a15XGJZz4wrnD6DY7g/view?usp=sharing

https://drive.google.com/file/d/1cdqloyiO8nTmuJmQ47zyKgAWGA-mIV35/view?usp=sharing

https://drive.google.com/file/d/1g8bPJNvuj60SDWWRCN-m15UcIfDMrJwJ/view?usp=sharing