2014 Ford Fiesta: Multiple RCM & IPC Fault Codes (U0253, U0127, U014-than, U0257) After APIM Replacement

I recently experienced two separate touchscreen display malfunctions on my 2014 Ford Fiesta, occurring within a three-month period. In both cases, the infotainment system was unresponsive and the UI lagged significantly. The second issue resolved temporarily with a battery reset, but the dealership replaced the APIM (Audio Processing Interface Module) as a precaution. After the replacement, my vehicle appeared to run normally at first. However, shortly after leaving the shop, I noticed new issues: the touchscreen and USB ports were completely dead, dashboard indicators for turn signals and headlights failed to work, sound from turn signals was absent, and auto-lock functionality stopped working. A second battery reset did not resolve these problems. I’ve repeatedly asked the dealership for a clear explanation, but received only vague or inconsistent responses. It appears that something went wrong during the APIM replacement process—yet no one will acknowledge this beyond stating that 'the BCM (Body Control Module) needs to be replaced' and that no further action can be taken until then. Using FORscan with a modified ELM327, I retrieved several diagnostic trouble codes (DTCs): One from the RCM (APIM U0253:00-0B), and three from the IPC (TPM U0127:87-0F, BCM U0140:87-0F, Front Controls / Display Interface Module U0257:87-0F). Additionally, a self-test on the IPC revealed two more codes—P081C:01 and B101E:01—which do not appear in the main DTC list. However, Ford has issued a TSB indicating that P081C may be triggered by performing a self-test while the vehicle is in park, suggesting these might not represent actual faults. All of these codes are related to the CAN bus network, which connects key modules including the RCM and IPC. Given this, I’m concerned about potential damage during the APIM replacement or improper wiring. What should I do next? Despite extensive Googling, much of the technical content is beyond my understanding. Based on articles from this site, it's clear that these modules are all part of the vehicle’s CAN bus system. How should I interpret these codes in context? Is there a known failure mode after APIM replacement involving BCM or RCM communication? What diagnostic steps can I take to identify the true root cause—especially since the dealership is refusing further investigation beyond replacing the BCM?