SpaceX has yet to disclose specific details about the incident, which a company source said took place on a Merlin test stand that has two bays. One bay reportedly suffered damage that will take two to four weeks to repair, while the neighboring bay received only minor damage that can be repaired in days.The incident, according to the source, took place not during an actual engine firing but during a troubleshooting activity called a "LOX drop" where liquid oxygen is flowed through the engine to look for leaks. It wasn't clear how this test led to the anomaly that damaged the engine and its test bay.
... Company sources say SpaceX can continue those launches, even while this investigation continues, because the engine that suffered the testing mishap was an upgraded version for the forthcoming "Block 5" version of the Falcon 9. The company is currently flying the Block 4 version of the rocket, and has not set a firm date for starting flights of the Block 5 version.
That would explain why the company is able to continue Falcon 9 launches even while the investigation, which may take several weeks to complete, continues, as the engine that failed is not used on existing versions of the rocket.