$500 via Verizon e-gift card (sent w/in 8 wks). Activation of 4G LTE/5G phone on One Unlimited for iPhone (all lines on account req'd on plan), 5G Do More, 5G Play More or 5G Get More plans req'd. Device must remain active for 45 days. $500 charge back if service cancelled w/in 12 mos or eligibility req's are no longer met. See vzw.com/bring-your-own-device for details.
It would probably be cheaper to replace the modem. Check to see if you are eligible for an upgrade or if you have a insurance. You can also check ebay to see if they have spare parts, but I would think that is more trouble then it is really worth.