Search for: "Android Head Unit PX5 Firmware" or "DHD 4300 MCU update" . XDA threads often have direct Google Drive links from trusted developers like "Malaysk" or "Hal9k".
Unlike high-end Android head units that may offer "Over-the-Air" (OTA) updates, the (a non-DVD, "deckless" unit) often needs its internal IC memory chip to be manually reflashed if the system becomes corrupted or unresponsive. Download Firmware Head Unit Dhd 4300